Generation and functional evaluation of novel monoclonal antibodies targeting glycosylated human stem cell factor

Human stem cell factor (hSCF) is an early-acting growth factor that promotes proliferation, differentiation, migration, and survival in several tissues. It plays a crucial role in hematopoiesis, gametogenesis, melanogenesis, intestinal motility, and in development and recovery of nervous and cardiovascular systems. Potential therapeutic applications comprise anemia treatment, mobilization of hematopoietic stem/progenitor cells to peripheral blood, and increasing gene transduction efficiency for gene therapy. Developing new tools to characterize recombinant hSCF in most native-like form as possible is crucial to understand the complexity of its in vivo functions and for improving its biotechnological applications. The soluble domain of hSCF was expressed in HEK293 cells. Highly purified rhSCF showed great molecular mass variability due to the presence of N- and O-linked carbohydrates, and it presented a 2.5-fold increase on proliferative activity compared to bacteria-derived hSCF. Three hybridoma clones producing monoclonal antibodies (mAbs) with high specificity for the glycoprotein were obtained. 1C4 and 2D3 mAbs were able to detect bacteria-derived and glycosylated rhSCF and demonstrated to be excellent candidates to develop a sandwich ELISA assay for rhSCF quantification, with detection limits of 0.18 and 0.07 ng/ml, respectively. Interestingly, 1A10 mAb only recognized glycosylated rhSCF, suggesting that sugar moieties might be involved in epitope recognition. 1A10 mAb showed the highest binding affinity, and it constituted the best candidate for immunodetection of the entire set rhSCF glycoforms in western blot assays, and for intracellular cytokine staining. Our work shows that combining glycosylated rhSCF expression with hybridoma technology is a powerful strategy to obtain specific suitable immunochemical assays and thus improve glycoprotein-producing bioprocesses. KEY POINTS: • Soluble glycosylated human SCF exerted improved proliferative activity on UT-7 cells. • Three mAbs with high specificity targeting glycosylated human SCF were obtained. • mAbs applications comprise sandwich ELISA, western blot, and immunofluorescence assays.

Cyclic AMP and c-KIT signaling in familial testicular germ cell tumor predisposition

BACKGROUND

Familial testicular germ cell tumors (FTGCTs) are hypothesized to result from the combined interaction of multiple low-penetrance genes. We reported inactivating germline mutations of the cAMP-binding phosphodiesterase 11A (PDE11A) as modifiers of FTGCT risk. Recent genome-wide association studies have identified single-nucleotide polymorphisms in the KITLG gene, the ligand for the cKIT tyrosine kinase receptor, as strong modifiers of susceptibility to both familial and sporadic testicular germ cell tumors.

DESIGN

We studied 94 patients with FTGCTs and 50 at-risk male relatives from 63 unrelated kindreds, in whom the PDE11A gene had been sequenced by investigating the association between KITLG genome-wide association study single-nucleotide polymorphisms rs3782179 and rs4474514 and FTGCT risk in these patients and in 692 controls. We also examined cAMP and c-KIT signaling in testicular tissues and cell lines and extended the studies to 2 sporadic cases, one with a PDE11A defect and one without, as a comparison.

RESULTS

We found a higher frequency of the KITLG risk alleles in FTGCT patients who also had a PDE11A sequence variant, compared with those with a wild-type PDE11A sequence. In NTERA-2 and Tcam-2 cells transfected with the mutated forms of PDE11A (R52T, F258Y, Y727C, R804H, V820M, R867G, and M878V), cAMP levels were significantly higher, and the relative phosphodiesterase activity was lower than in the wild-type cells. KITLG expression was consistently increased in the presence of PDE11A-inactivating defects, both at the RNA and protein levels, in familial testicular germ cell tumors. The 2 sporadic cases that were studied, one with a PDE11A defect and another without, agreed with the data in FTGTCT and in the cell lines.

CONCLUSIONS

Patients with FTGCT and PDE11A defects also carry KITLG risk alleles more frequently. There may be an interaction between cAMP and c-KIT signaling in predisposition to testicular germ cell tumors.

Evaluation of the KIT/stem cell factor axis in renal tumours

AIM

To investigate the expression of the KIT/stem cell factor (SCF) axis in different renal cell carcinoma subtypes with regard to targeted therapies.

MATERIALS AND METHODS

The expression of KIT and SCF were immunhistochemically assessed in 40 clear cell (ccRCC), 25 papillary (pRCC) and 19 chromophobe carcinomas (chRCC); 27 oncocytomas and 32 benign kidney parenchyma specimens differentiated into distal tubules (DT) and proximal tubules (PT).

RESULTS

The expression of KIT was significantly higher in chRCC and oncocytoma compared to ccRCC and pRCC. All tumours exhibited a significant increase of membranous to cytoplasmic KIT expression, with the highest in ccRCC and pRCCs. SCF was expressed in all tumour subgroups, with the highest in oncocytomas and pRCC. SCF correlated positively with the cytoplasmic expression of KIT. A higher tumour stage correlated to lower KIT expression in ccRCC.

CONCLUSION

Simultaneous expression of SCF and KIT in renal tumours, which seems to undergo a shift from the cytoplasm to the cell membrane, suggests paracrine and autocrine mechanisms in KIT activation, with different, as yet unknown, regulatory mechanisms in the different tumour entities.

Stem cell factor/c-Kit signalling in normal and androgenetic alopecia hair follicles

Androgens stimulate many hair follicles to alter hair colour and size via the hair growth cycle; in androgenetic alopecia tiny, pale hairs gradually replace large, pigmented ones. Since stem cell factor (SCF) is important in embryonic melanocyte migration and maintaining adult rodent pigmentation, we investigated SCF/c-Kit signalling in human hair follicles to determine whether this was altered in androgenetic alopecia. Quantitative immunohistochemistry detected three melanocyte-lineage markers and c-Kit in four focus areas: the epidermis, infundibulum, hair bulb (where pigment is formed) and mid-follicle outer root sheath (ORS). Colocalisation confirmed melanocyte c-Kit expression; cultured follicular melanocytes also exhibited c-Kit. Few ORS cells expressed differentiated melanocyte markers or c-Kit, but NKI/beteb antibody, which also recognises early melanocyte-lineage antigens, identified fourfold more cells, confirmed by colocalisation. Occasional similar bulbar cells were seen. Melanocyte distribution, concentration and c-Kit expression were unaltered in balding follicles. Androgenetic alopecia cultured dermal papilla cells secreted less SCF, measured by ELISA, than normal cells. This identifies three types of melanocyte-lineage cells in human follicles. The c-Kit expression by dendritic, pigmenting, bulbar melanocytes and rounded, differentiated, non-pigmenting ORS melanocytes implicate SCF in maintaining pigmentation and migration into regenerating hair bulbs. Less differentiated, c-Kit-independent cells in the mid-follicle ORS stem cell niche and occasionally in the bulb, presumably a local reserve for long scalp hair growth, implicate other factors in activating stem cells. Androgens appear to reduce alopecia hair colour by inhibiting dermal papilla SCF production, impeding bulbar melanocyte pigmentation. These results may facilitate new treatments for hair colour changes in hirsutism, alopecia or greying.

Endothelial progenitor cells in pterygium pathogenesis

PURPOSE

The pathogenesis of pterygium is not well known, and controversy exists about the cell origins and the nature of initial trigger required for its development. We investigated whether endothelial progenitor cells (EPCs) are involved in pathogenesis of pterygium and the mechanism underlying the selective recruitment of EPCs during this process.

METHODS

We studied 13 normal controls and 28 pterygium patients (primary (n=15), recurrent (n=13)). Substance-P, vascular endothelial growth factor (VEGF), and stem cell factor (SCF) were measured in plasma and tears using ELISA, and circulating CD34(+) and c-kit(+) mononuclear cells (MNCs) by flow cytometry. Anterior segment fluorescein angiography (FAG) was performed to evaluate hypoxic conditions in the early stage of pterygium. Surgically removed pterygial tissues were analyzed immunohistochemically using the progenitor cell markers, CD34, c-kit, VEGFR-1, and VEGFR-2.

RESULTS

Anterior segment FAG findings showed an increase in non-perfusion areas and attenuated vessels in the nasal limbus during early-stage pterygium. Circulating CD34(+) MNCs and c-kit(+) MNCs were increased in pterygium groups compared with normal controls. Systemic and local cytokines including SP, VEGF, and SCF in pterygium groups were also elevated and showed positive correlations with CD34(+) and c-kit(+) MNC numbers. Immunohistochemical analysis of pterygium showed strong progenitor cell marker immunoreactivities.

CONCLUSIONS

EPCs might be involved in pterygium development, and ocular hypoxia triggers this neovascularization by recruiting EPCs derived from the bone marrow via the production of systemic and local cytokines.

Differential gene expression in transition of primordial to preantral follicles in mouse ovary

In the mammalian ovary, early follicular development is gonadotropin independent. Interaction between the oocyte and granulosa cells possibly plays an important role in transition of primordial to preantral stage. However, the molecular and cellular control of early follicular development and cell-cell interaction is complex and poorly understood. In the present study, we examined gene expression in primordial, primary and preantral follicle by cDNA arrays using Day 2, Day 4 and Day 6 neonatal mouse ovaries that contain the various developmental stages of these follicles, respectively. The results revealed that 30% of the genes were differentially expressed in Day 4 ovaries containing primary follicles as compared to D2 neonatal ovaries. The data were confirmed by the expression of Growth Differentiation Factor-9 in the oocytes of primary and preantral follicles. Also, Stem Cell Factor was localized in the granulosa cells of primary and preantral follicles. Electron microscopic studies of Day 6 ovaries showed projections from granulosa cells and microvilli from oocytes in the follicle during the transition from the primary to preantral stage. Further, initiation of gap junctions were observed at ultrastructure level and corroborated with the expression of specific gap junction protein, connexin 43 in preantral follicles of the ovaries. These results infer that primordial follicles are quiescent while the major activities of cell-cell communication and the production of local paracrine factors, are initiated in primary and preantral follicles of the mouse ovary. These preliminary observations may contribute to the elucidation of molecular and cellular pathways involved in follicle transition.

[Biological properties of mesenchymal stem cells derived from bone marrow of patients with multiple myeloma]

The study was purposed to explore the role of mesenchymal stem cells (MSCs) in the pathogenesis of bone disease particularly observed in multiple myeloma (MM), the biological features of marrow derived MSCs from patients with MM have been investigated. Marrow aspirates were harvested from 11 newly diagnosed patients with MM and 5 normal adults and MSCs were isolated and culture-expanded by the cell properties of adherence to plastic flasks, The phenotype was analyzed by flow cytometric technique. The proliferation of MSCs was observed by MTT assay and their differentiation capacities into osteoblasts and adipoblasts were assessed with lineage-specific histochemical staining. The concentrations of IL-6 and SCF in the culture supernatant were detected by enzyme-linked immunosorbent assay (ELISA). MSC culture supernatants were collected and MTT assay was performed to evaluate their support on the proliferation of an MM cell line SKO007 cells. The results showed that bone marrow-derived MSCs from MM patients were homogeneously positive for CD29, CD73, CD166 and HLA-ABC and negative for hematopoietic cell marker CD45 and endothelial cell marker CD31, the phenotype of which was similar to that of marrow counterparts from normal adults. MTT assay indicated that MSCs from MM patients or normal adults proliferated at similar rates. MSCs from MM patients occupied in vitro osteogenic and adipogenic capacity as those from normal adults. The levels of IL-6 and SCF in culture supernatant were greatly up-regulated in MM patients by ELISA assay. Furthermore, MSC culture supernatants from MM bone marrow displayed enhanced activity to promote the proliferation of SKO007 cells. It is concluded that marrow-derived MSCs from bone marrow of MM patients are normal in their proliferation and differentiation capacities, and myeloma bone disease may not be ascribed to the differentiation of MSCs while the elevated secretion of IL-6 and SCF may provide necessary cues for the survival of malignant myeloma cells.

KIT/stem cell factor expression in premalignant and malignant lesions of the colon mucosa in relationship to disease progression and outcomes

Autocrine/paracrine stimulation of KIT has been observed in colorectal carcinoma (CRC) cell lines. We investigated the expression of KIT and stem cell factor (SCF) in CRC in comparison with premalignant colon lesions and normal colonic mucosa to assess the prognostic and therapeutic relevance of this receptor/ligand system in CRC. Transcript levels of c-kit and the two SCF splicing variants were determined quantitatively by real-time RT-PCR using cDNA obtained from normal, premalignant and malignant snap frozen colon tissue specimens. Immunohistochemistry with specific anti-KIT and anti-SCF antibodies was performed on paraffin-embedded tissue sections in order to localize the relative protein expression in epithelial compartments. Approximately 10% of patients expressed KIT in their adenoma or primary tumor. The majority of KIT-positive carcinomas co-expressed SCF. Real-time RT-PCR showed expression of c-kit and SCF transcripts in all cDNA specimens examined. A significant association between the co-expression of KIT/SCF and a worse clinical outcome was found. In conclusion, KIT expression was observed in a proportion of premalignant and malignant colonic lesions, while it was virtually absent in normal colon mucosa. Moreover, the majority of KIT-positive carcinomas co-expressed SCF, suggesting the possibility of aberrant signaling by an autocrine loop, as confirmed by the negative prognostic value of this association. Therefore, in the subset of CRC patients with concomitant KIT/SCF expression, the activity of Imatinib mesylate, a selective inhibitor of specific tyrosine kinases including KIT, may be exploited in combination with standard therapy.

Expression of stem cell factor and its receptor, c-kit, in human oral mesenchymal cells

Stem cell factor (SCF) is the pleiotropic ligand for the tyrosine kinase receptor, c-kit. Ligand and receptor are usually expressed in different cell types, and binding of SCF to c-kit promotes cell proliferation, differentiation, and recruitment of progenitor cells in various biologic systems. However, the localization of these two molecules in cells of the oral cavity has not been systematically examined. We investigated the expression of SCF and c-kit in human dental pulp (HDP) cells as well as in human gingival fibroblasts (HGF). Both alternatively spliced isoforms of SCF were detected (through reverse transcription-polymerase chain reaction) in RNA obtained from the two cell types. Western analysis established that both cell types express SCF and/or c-kit, whereas flow cytometry demonstrated distinct cell populations expressing only the ligand (SCF), only the receptor (c-kit), or co-expressing the two. HDP cultures showed higher soluble SCF (sSCF) production associated with faster cell growth, as compared with HGF cultures. In both cell types, however, sSCF levels appeared to increase as a result of in vitro aging and/or differentiation.

Co expression of SCF and KIT in gastrointestinal stromal tumours (GISTs) suggests an autocrine/paracrine mechanism

KIT is a tyrosine kinase receptor expressed by several tumours, which has for specific ligand the stem cell factor (SCF). KIT is the main oncogene in gastrointestinal stromal tumours (GISTs), and gain-of-function KIT mutations are present in 70% of these tumours. The aim of the study was to measure and investigate the mechanisms of KIT activation in 80 KIT-positive GIST patients. KIT activation was quantified by detecting phosphotyrosine residues in Western blotting. SCF production was determined by reverse transcriptase-PCR, ELISA and/or immunohistochemistry. Primary cultures established from three GISTs were also analysed. The results show that KIT activation was detected in all cases, even in absence of KIT mutations. The fraction of activated KIT was not correlated with the mutational status of GISTs. Membrane and soluble isoforms of SCF mRNA were present in all GISTs analysed. Additionally, SCF was also detected in up to 93% of GISTs, and seen to be present within GIST cells. Likewise, the two SCF mRNA isoforms were found to be expressed in GIST-derived primary cultures. Thus, KIT activation in GISTs may in part result from the presence of SCF within the tumours.

The activin-follistatin system and in vitro early follicle development in goats

The aim of the present study was to investigate the effects of activin-A and follistatin on in vitro primordial and primary follicle development in goats. To study primordial follicle development (experiment 1), pieces of ovarian cortex were cultured in vitro for 5 days in minimal essential medium (MEM) supplemented with activin-A (0, 10 or 100 ng/ml), follistatin (0, 10 or 100 ng/ml) or combinations of the two. After culture, the numbers of primordial follicles and more advanced follicle stages were calculated and compared with those in non-cultured tissue. Protein and mRNA expression of activin-A, follistatin, Kit ligand (KL), growth differentiation factor-9 (GDF-9) and bone morphogenetic protein-15 (BMP-15) in non-cultured and cultured follicles were studied by immunohistochemistry and PCR. To evaluate primary follicle growth (experiment 2), freshly isolated follicles were cultured for 6 days in MEM plus 100 ng/ml activin-A, 100 ng/ml follistatin or 100 ng/ml activin-A plus 200 ng/ml follistatin. Morphology, follicle and oocyte diameters in cultured tissue and isolated follicles before and after culture were assessed. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) reactions were performed to study DNA fragmentation in follicles. In experiment 1, it was found that goat primordial follicles were activated to develop into more advanced stages, i.e. intermediate and primary follicles, during in vitro culture, but neither activin-A nor follistatin affected the number of primordial follicles that entered the growth phase. Activin-A treatment enhanced the number of morphologically normal follicles and stimulated their growth during cortical tissue culture. The effects were, however, not counteracted by follistatin. The follicles in cultured goat tissue maintained their expression of proteins and mRNA for activin-A, follistatin, KL, GDF-9 and BMP-15. Fewer than 30% of the atretic follicles in cultured cortical tissue had TUNEL-positive (oocyte or granulosa) cells. Activin-A did not affect the occurrence of TUNEL-positive cells in follicles within cortical tissue. In experiment 2, addition of activin-A to cultured isolated primary follicles significantly stimulated their growth, the effect being counteracted by follistatin. Absence of such a neutralizing effect of follistatin in the cultures with ovarian cortical tissue can be due to lower dose of follistatin used and incomplete blockage of activin in these experiments. In contrast to cortical enclosed atretic follicles, all atretic follicles that had arisen in cultures with isolated primary follicles had TUNEL-positive cells, which points to differences between isolated and ovarian tissue-enclosed follicles with regard to the followed pathways leading to their degeneration. In summary, this in vitro study has demonstrated that cultured goat primordial follicles are activated to grow and develop into intermediate and primary follicles. During in vitro culture, the follicles maintain their ability to express activin-A, follistatin, KL, GDF-9 and BMP-15. The in vitro growth and survival of activated follicles enclosed in cortical tissue and the in vitro growth of isolated primary follicles are stimulated by activin-A.

Kit ligand and c-Kit are expressed during early human ovarian follicular development and their interaction is required for the survival of follicles in long-term culture

The receptor tyrosine c-Kit and its cognate ligand, c-Kit ligand (KL, stem cell factor, SCF), are involved in ovarian follicular development in several animal species. We studied the expression of KL and c-Kit usingin situhybridization and immunohistochemistry in donated human ovarian cortical tissue. The KL transcripts were expressed in granulosa cells of primary follicles, whereas the expression of c-Kit was confined to the oocyte and granulosa cells in primary and secondary follicles. We employed an ovarian organ culture using firstly serum-containing and then serum-free medium to study the effects of KL and an anti-c-Kit antibody, ACK2, on the development and survival of ovarian folliclesin vitro. Culture of ovarian cortical slices for 7 days resulted in a 37% increase in the number of primary follicles and a 6% increase in secondary follicles. The proportion of viable follicles decreased in all cultures. The addition of KL (1, 10 and 100 ng/ml) into the culture media did not affect the developmental stages of the follicles or the proportion of atretic follicles. Inclusion of ACK2 (800 ng/ml) in the culture medium significantly increased the proportion of atretic follicles on days 7 (49 vs 28% in control cultures) and 14 (62 vs 38%) of culture. In conclusion, c-Kit and KL are expressed in human ovaries during follicular development. Blocking the c-Kit receptor induces follicular atresia. The KL/c-Kit signaling system is likely to control the survival of human ovarian follicles during early follicular development.

Oval cells in hepatitis B virus-positive and hepatitis C virus-positive liver cirrhosis: histological and ultrastructural study

AIMS

It is still not clear whether oval cells demonstrate diverse morphology, immunophenotype or quantity in different human liver diseases. The aim of this study was to investigate these differences in hepatitis B virus (HBV)-positive and hepatitis C virus (HCV)-positive human liver cirrhosis (HLC).

METHODS AND RESULTS

Thirty-eight cases of HBV+ HLC and 32 cases of HCV+ HLC were investigated by light microscopy and immunohistochemistry for Hepatocyte, CK19, stem cell factor (SCF) and CD34. Five cases were also examined by transmission electron microscopy. Oval cells of similar morphology could be found in proliferating bile ductules in both groups. These cells coexpressed CK19 and Hepatocyte, but did not express SCF or CD34. Some of these cells exhibited a trend towards differentiation. There was no difference in the amount of oval cells between the two groups. The oval cell number was found to increase significantly with the progression of inflammation. A similar stem-like cell was not seen in the normal liver.

CONCLUSIONS

There are bipotential oval cells in both HBV+ and HCV+ HLC. The lack of difference in oval cells between the two groups suggests that they might play a similar biological role in the histogenesis of different liver diseases.

Correlation between age and the secretions of melanocyte-stimulating cytokines in cultured keratinocytes and fibroblasts

BACKGROUND

The majority of skin changes associated with ageing are caused by photoageing and reflect cumulative sun exposure. Although the actinic damage plays a major role in skin pigmentation, it is also important to examine the effects of chronological cellular ageing on the pigmentation. The chief cellular components of the skin other than melanocytes are keratinocytes and fibroblasts, and the influences of age-related changes in those cells on skin pigmentation have not been elucidated.

OBJECTIVE

To clarify the effects of cellular ageing of keratinocytes and fibroblasts on age-related skin pigmentation.

METHODS

Using ELISA analysis, we measured the level of melanogenic cytokines secreted by cultured keratinocytes and fibroblasts derived from skin of various chronological ages. We also compared the cytokine secretion by cultured keratinocytes between the second and fifth cultures.

RESULTS

There was no correlation between age and hepatocyte growth factor (HGF), stem cell factor (SCF), and basic fibroblast growth factor (bFGF) secretion by fibroblasts. On the other hand, a significant positive correlation existed between age and interleukin ((IL)-1alpha secretion (R2=0.50, P=0.002), and a relatively weak correlation existed between age and endothelin-1 (ET-1) secretion (R2=0.17, P=0.051, not significant). The IL-1alpha secretion by keratinocytes was significantly increased in the fifth cultures compared with the second cultures (P<0.005).

CONCLUSIONS

These findings suggest that IL-1alpha secretion increases as cells grow older, and the increased secretion of IL-1alpha by aged keratinocytes may stimulate HGF production in dermal fibroblasts paracrinely and ET-1 production in keratinocytes autocrinely, which stimulates melanocyte proliferation and induces an increase of tyrosinase activity in melanocytes. Because IL-1alpha is a primary mediator that responds to inflammation and injury, the transcription of genes involved in skin inflammation may be persistently induced in the aged skin. Thus the increased secretion of IL-1alpha by aged keratinocytes in the aged skin may play a role in the accentuated cutaneous pigmentation and other skin ageing.

Reduced stem cell factor links smooth myopathy and loss of interstitial cells of cajal in murine diabetic gastroparesis

BACKGROUND & AIMS

Diabetic gastroparesis involves neuropathy, myopathy, and depletion of interstitial cells of Cajal (ICC), which may cause dysrhythmias and impaired neural control. Most murine gastric ICC depend on stem cell factor (SCF) signaling but can also be maintained with insulin or insulin-like growth factor-I (IGF-I). We investigated whether SCF could mediate the actions of insulin and IGF-I.

METHODS

Expression of insulin receptor, IGF-I receptor, and SCF was studied in gastric muscles and purified ICC by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). The effects of insulin/IGF-I deficiency on SCF, ICC, smooth muscle, and neurons were investigated in nonobese diabetic mice and organotypic cultures by immunohistochemistry, microarrays, and/or quantitative RT-PCR. ICC in organotypic cultures were also studied after immunoneutralization of endogenous SCF.

RESULTS

Insulin and IGF-I receptors were detected in smooth-muscle cells and myenteric neurons but not in ICC. Cell-surface expression of SCF was only found in smooth-muscle cells. ICC depletion in diabetes was accompanied by smooth-muscle atrophy and reduced SCF, whereas neuron-specific gene expression remained unchanged. In organotypic cultures, prevention of ICC loss by insulin or IGF-I was paralleled by rescue of smooth-muscle cells and SCF expression but not of myenteric neurons. Immunoneutralization of endogenous SCF caused ICC depletion closely resembling that elicited by insulin/IGF-I deficiency.

CONCLUSIONS

Reduced insulin/IGF-I signaling in diabetes may lead to ICC depletion and its consequences by causing smooth-muscle atrophy and reduced SCF production. Thus, myopathy may play a more central role in diabetic gastroenteropathies than previously recognized.

Biological characterization of cultured dermal papilla cells and hair follicle regeneration in vitro and in vivo

BACKGROUND

Dermal papilla cells (DPC) are a group of mesenchyme-derived cells at the base of the hair follicle, where they regulate and control hair follicle growth through the expression and secretion of cytokines. Nevertheless, the role of DPC derived chemokines and other cytokines in the hair follicle biology remain speculative. In this study, we investigated the expression of basic fibroblast growth factor (bFGF), endothelin-1 (ET-1) and stem cell factor (SCF) in different passages of cultured DPC and their effects on the biological behaviour of DPC.

METHODS

The expression of bFGF, ET-1 and SCF in different passages of cultured DPC and their possible effects on the biological behavior of DPC are investigated using in situ hybridization and immunochemistry. In addition, we performed transplantation of hair follicle cells into nude mice. The cultured DPC, dermal sheath cells and fibroblast of human scalp, respectively, were mixed with cells of the hair follicle epithelium in different ratios, and then were cultured in hair follicle organotypic cultures or implanted into the subcutis of nude mice.

RESULTS

The expression of ET-1 and SCF in early passages of cultured DPC became stronger, but turned weaker and even negative in late passages (> 6 passages). Hair follicle-like structures were formed after DPC combined with the cells of hair follicle epithelium cells in hair follicle organotypic cultures. When hair follicle organotypic cultures were implanted into the subcutis of nude mice, the relative intact hair follicles were formed. After the transplantation of hair follicle cells into the nude mice, the hair follicle-like structure was formed in the group that contained DPC mixed with hair follicle epithelium cells. However, no hair follicles were formed in the other two groups. It was found that the higher the expression of ET-1 and SCF in DPC, the stronger the ability of DPC to induce hair follicle regeneration.

CONCLUSIONS

The cultured DPC can induce hair follicle regeneration and sustain hair growth in vivo and in vitro. Moreover, the expression of ET-1 and SCF is correlated with the ability of DPC inducing hair follicle regeneration.

Co-expression of c-kit and stem cell factor in primary and metastatic nasopharyngeal carcinomas and nasopharyngeal epithelium

Expression of c-kit has been demonstrated in 33% of adult nasopharyngeal carcinomas (NPCs) and in 88% of paediatric NPCs. Patients with tumours expressing c-kit tend to exhibit better survival, but a paracrine/autocrine function for the stem cell factor (SCF)/c-kit system in nasopharyngeal carcinomas has not been reported. This study evaluated the expression of c-kit and SCF by immunohistochemical staining of nasopharyngeal epithelium (NPE) and of primary and metastatic NPCs. In addition, c-kit and SCF expression were studied in HONE-1 NPC cells by immunoprecipitation and western blotting. Expression of c-kit and SCF was detected in 75% and 57% of NPE, respectively, and there was 48% co-expression. In primary NPCs, 86% expressed c-kit, 69% had SCF expression, and there was 67% co-expression. In metastatic NPCs, 76% expressed c-kit, 72% expressed SCF and there was 68% co-expression. Co-expression of c-kit and SCF with tyrosine autophosphorylation of p145(c - kit) was demonstrated in HONE-1 NPC cells. In addition, the expression level of c-kit and its autophosphorylation status was not obviously influenced by the transient co-expression of Epstein-Barr nuclear antigen 1 (EBNA1) and latent membrane protein 1 (LMP1). Co-expression of c-kit and SCF is therefore commonly found in nasopharyngeal epithelium and NPCs, and in HONE-1 NPC cells with autoactivation possibly independent of the co-expression of EBNA1 and LMP1. All of these findings suggest that autoactivation of SCF/c-kit signalling may be a potent regulator of the nasopharyngeal epithelial barrier and of immune function at the nasopharyngeal mucosa surface, and may contribute to the carcinogenesis and progression of NPC. Further molecular analysis is required to evaluate the possibility of treatment with tyrosine kinase inhibitors in NPC, analogous to the treatment of gastrointestinal stromal tumours with STI571.

Immunohistochemical evidence for an endocrine/paracrine role for ghrelin in the reproductive tissues of sheep

BACKGROUND

The gut hormone, ghrelin, is involved in the neuroendocrine and metabolic responses to hunger. In monogastric species, circulating ghrelin levels show clear meal-related and body weight-related changes. The pattern of secretion and its role in ruminant species is less clear. Ghrelin acts via growth hormone secretagogue receptors (GHSR-1a) to alter food intake, fat utilization, and cellular proliferation. There is also evidence that ghrelin is involved in reproductive function. In the present study we used immunohistochemistry to investigate the presence of ghrelin and GHSR-1a in sheep reproductive tissues. In addition, we examined whether ghrelin and GHSR-1a protein expression is developmentally regulated in the adult and fetal ovine testis, and whether there is an association with markers of cellular proliferation, i.e. stem cell factor (SCF) and proliferating cell nuclear antigen (PCNA).

METHODS

Antibodies raised against ghrelin and its functional receptor, GHSR-type 1a, were used in standard immunohistochemical protocols on various reproductive tissues collected from adult and fetal sheep. GHSR-1a mRNA presence was also confirmed by in situ hybridisation. SCF and PCNA immunoexpression was investigated in fetal testicular samples. Adult and fetal testicular immunostaining for ghrelin, GHSR-1a, SCF and PCNA was analysed using computer-aided image analysis. Image analysis data were subjected to one-way ANOVA, with differences in immunostaining between time-points determined by Fisher's least significant difference.

RESULTS

In adult sheep tissue, ghrelin and GHSR-1a immunostaining was detected in the stomach (abomasum), anterior pituitary gland, testis, ovary, and hypothalamic and hindbrain regions of the brain. In the adult testis, there was a significant effect of season (photoperiod) on the level of immunostaining for ghrelin (p < 0.01) and GHSR-1a (p < 0.05). In the fetal sheep testis, there was a significant effect of gestational age on the level of immunostaining for ghrelin (p < 0.001), GHSR-1a (p < 0.05), SCF (p < 0.05) and PCNA (p < 0.01).

CONCLUSION

Evidence is presented for the presence of ghrelin and its receptor in various reproductive tissues of the adult and fetal sheep. In addition, the data indicate that testicular expression of ghrelin and its receptor is physiologically regulated in the adult and developmentally regulated in the fetus. Therefore, the ghrelin ligand/receptor system may have a role (endocrine and/or paracrine) in the development (cellular proliferation) and function of the reproductive axis of the sheep.

Application of novel tissue microarrays to investigate expression of tryptase, chymase and KIT protein in placental mast cells

INTRODUCTION

Tissue microarrays comprise numerous small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allow high throughput analysis of multiple specimens at the same time. Mast cells are paracrine cells found ubiquitously in connective tissue. Expression of the serine proteases tryptase and chymase, as well as KIT protein, the receptor for stem cell factor (SCF), has been demonstrated in mast cells. Because little is known about the role of mast cells in the placenta, we investigated the number and expression of chymase, tryptase, and KIT protein in placental mast cells using newly developed tissue microarrays.

MATERIALS AND METHODS

Tissue microarrays were prepared from archival paraffin tissue blocks of 90 placentae, including 15 normal ones as a control group. Gestational age of the placentae ranged from 7 to 42 weeks. Sections of formalin-fixed paraffin-embedded material were prepared on chemically activated cover-slides. The slides were cut in 4-mm(2) squares containing representative areas, and transferred to a tissue microarray. Hematoxylin and eosin (H&E), chloroacetate esterase (CAE), toluidine blue, periodic acid--Schiff (PAS), and immunohistochemical staining were performed. The number of mast cells and expression of chymase, tryptase, and KIT protein were evaluated in each case.

RESULTS

Mast cell numbers in placentae with inflammation/abortion exceeded that of normal placentae. Although statistically not significant, we furthermore observed an increase in chymase-positive mast cells in the group of placentae associated with fetal malformations/chromosomal aberrations compared with normal placentae.

DISCUSSION

Novel tissue microarray technique has been introduced into placental research, and allows multiple placental tissue samples to be effectively analyzed simultaneously. This study indicated an increased number of chymase-positive mast cells in placentae with fetal malformation/chromosomal aberration. Activation of angiotensin II by chymase may play a role in fetal malformation. Moreover, it has been speculated that mast cells may only express chymase (MC(C)). Our findings denote the presence of placental MC(C). However, further studies are needed to elucidate more precisely the role of mast cell chymase in the placenta.

Quantification of stem cell factor mRNA levels in the rat testis: usefulness of clusterin mRNA as a marker of the amount of mRNA of Sertoli cell origin in post pubertal rats

Spermatogenesis is a complex cellular process regulated by gonadotrophins and local cell-cell interactions. Stem cell factor (SCF) is one of the paracrine factors, produced by the Sertoli cells, involved in the local regulation of spermatogenesis. Measurement of its testicular level is important for addressing its role in testis physiopathology. However, the relative cell composition of experimental and pathological testis samples may lead to misinterpretation in relating SCF mRNA levels to the amount of RNA extracted from the whole tissue sample. Taking into account the relative RNA content of Sertoli cell origin should provide more significant data. In the present study, three sets of experiments were intended for modifying the proportion of RNA of Sertoli cell origin in RNA extracted from whole testis tissue samples: during postnatal development; following methoxy-acetic acid (MAA) administration; and after injecting a long-acting gonadotrophin-releasing hormone agonist (GnRHa). In a first step, we demonstrated clusterin mRNA level stability in purified Sertoli cell preparations between 20 days and adulthood, and following MAA or GnRHa treatment. In a second step, we used a competitive RT-PCR assay to measure SCF and clusterin mRNA levels and expressed the amount of SCF mRNA relative to the amount of clusterin mRNA under the above experimental conditions. The SCF/clusterin mRNA level ratio was found to remain roughly stable from 20 days post-partum to adulthood; i.e. during the development of spermatogenesis. MAA administration led to an overall increase in the SCF/clusterin mRNA level ratio between 7 and 14 days after administration, consistent with the replenishment of the testis with pachytene spermatocytes and round spermatids. Conversely, after long-acting GnRHa injection, the SCF/clusterin mRNA level ratio decreased only slightly from day 21 onward. Hence, the present studies indicate that, under physiopathological conditions, the amount of clusterin mRNA is a good marker of the amount of RNA of Sertoli cell origin in testis samples at day 20 or later; different experimental alterations of spermatogenesis are associated with different patterns of SCF mRNA levels; the relationship between FSH and SCF in vivo is not as simple as that described in vitro.

Analysis of the lineage relationship between mast cells and basophils using the c-kit D816V mutation as a biologic signature

BACKGROUND

Mast cells and basophils share similar morphologic and functional properties; however, it is not known whether they are derived from a bilineage (basophil/mast cell)-restricted progenitor.

OBJECTIVE

To assess whether basophils and mast cells are derived from common committed progenitors using the c-kit D816V mutation as a biologic signature.

METHODS

The D816V c-kit mutation found in mast cells of patients with systemic mastocytosis is used as a trackable genetic marker to assess the lineage relationship between mast cells and basophils. Blood and bone marrow aspirates were collected from 33 consecutive patients with mastocytosis with different disease severity. Peripheral blood basophils, monocytes and neutrophils were sorted by immunomagnetic beads. Presence of the D816V c-kit mutation was analyzed by restriction fragment length polymorphism in the genomic DNA and mRNA from sorted cells in all patients and in the genomic DNA of individual basophils of 1 patient.

RESULTS

The c-kit D816V mutation was detectable in basophils of 5 patients (15%). All 5 patients had the c-kit mutation also detectable in monocytes and thus had multilineage involvement. Single cell analysis of the genomic DNA in 1 patient showed a similar degree of clonal expansion in basophils, monocytes, and neutrophils. Mutated c-kit was expressed at the mRNA level in all 5 patients. There was no difference in surface Kit expression levels in basophils.

CONCLUSION

Basophils carrying the D816V c-kit mutation in mastocytosis were detected only in the context of a multilineage involvement. These results argue against the presence of a bilineage-restricted committed progenitor for mast cells and basophils.

Less keratinocyte-derived factors related to more keratinocyte apoptosis in depigmented than normally pigmented suction-blistered epidermis may cause passive melanocyte death in vitiligo

Stem cell factor (SCF) of keratinocyte origin regulates melanocyte growth and survival. Deprivation of survival factors causes the apoptosis of melanocytes. Vitiligo often develops following physical trauma, even if this is minor. The exact mechanism of the Koebner phenomenon in vitiligo is unclear. Apoptosis of keratinocytes, which occurs more in depigmented suction-blistered epidermis than in the normally pigmented counterpart, could reduce levels of keratinocyte-derived factors such as SCF and basic fibroblast growth factor (bFGF). Levels of SCF expression were examined in the depigmented and normally pigmented paired epidermis of 19 patients with vitiligo, and bFGF expression in six patients. The expression of SCF (p<0.001) and bFGF was usually reduced in the depigmented compared with the normally pigmented epidermis. Apoptosis of cultured normal human keratinocytes, which was induced by staurosporine, resulted in a concentration-dependent decrease in levels of SCF mRNA and protein. Normal human melanocytes proliferated more in medium containing SCF or keratinocyte (XB-2) feeder than in medium with neither. Deprivation of SCF or keratinocyte feeder in the culture medium induced a marked decrease in melanocytes as a result of apoptosis. Therefore, lower expression of keratinocyte-derived factors, including SCF, in vitiliginous keratinocytes, which could result from keratinocyte apoptosis, might be responsible for passive melanocyte death and may explain the Koebner phenomenon.

Expression and mutational analysis of tyrosine kinase receptors c-kit, PDGFRalpha, and PDGFRbeta in ovarian cancers

Most women with epithelial ovarian cancer are diagnosed with advanced disease. Despite surgery and initial tumor reduction by standard chemotherapy, the tumors frequently recur and the patients eventually die of their disease. New drugs that inhibit tyrosine kinase receptors (TKRs) are being investigated for treatment and this study was undertaken to determine the expression and mutational state for 3 TKRs (c-kit, platelet-derived growth factor receptor [PDGFR] alpha, and PDGFR beta) in ovarian cancer. Tissue arrays containing 84 epithelial ovarian tumors were studied by immunohistochemistry with antibodies specific for c-kit, PDGFR alpha, and PDGFR beta. Immunoreactivity was detected in 78% of the tumor to at least one TKR. PDGFR alpha was expressed in the largest percentage of ovarian tumors (58%) whereas 29% expressed PDGFR beta. Two commercial antibodies against c-kit were studied and 33% of the tumors stained with one but only 6% were interpreted as positive with the second antibody. Activation of TKRs may occur through mutations but, by sequence analysis, no mutations were detected in 6 ovarian tumors with elevated immunoreactivity for each of the TKRs (c-kit, PDGFR alpha, and PDGFR beta). Tyrosine kinase receptors could also be activated through autocrine or paracrine stimulation of receptor by its ligand. Of 43 (35%) tumors tested for both c-kit receptor and its ligand (stem cell factor), 15 expressed both proteins indicating the possibility that this autocrine stimulation feedback loop is a factor in the growth of some ovarian cancers. This study demonstrates that PDGFR alpha, PDGFR beta, and c-kit are expressed in a high percentage of epithelial ovarian cancers suggesting that tyrosine kinase inhibitors may be useful in the treatment of these tumors.

Stem cell factor and c-Kit in human primordial germ cells and fetal ovaries

The distribution of the tyrosine kinase receptor c-Kit and its ligand stem cell factor (SCF) was evaluated by immunohistochemistry in primordial germ cells (PGCs) and human embryonic gonads during weeks 5-8 of prenatal life, and fetal ovaries during weeks 9-36 of prenatal life. Distinct c-Kit and SCF staining was present in primordial germ cells in the wall of the hindgut and in the dorsal mesentery, particularly on level with the 10th thoracic columnar segment. Several PGCs were in close contact with c-Kit-negative but SCF-positive autonomic nerve fibers of the dorsal mesentery. Many fibroblasts and mesothelial cells of the dorsal mesentery were clearly stained for SCF, but not for c-Kit. Prominent c-Kit and SCF staining was present in germ cells of the embryonic gonadal anlage and in oogonia during further ovarian development. However, oocytes were either unstained or faintly stained for SCF. Oocytes not yet enclosed in follicles or present in primordial follicles were either unstained or exhibited faint cytoplasmic c-Kit staining, whereas oocytes of growing preantral follicles again showed distinct cell membrane staining which decreased during further follicular growth. Theca cells did not stain for c-Kit. Some pregranulosa cells and the first formed granulosa cells of primordial follicles were c-Kit stained. Granulosa cells of other follicles were not c-Kit stained. In the inner part of the cortex, SCF immunolabeling was detected in some pregranulosa cells surrounding cords containing germ cells and involved in formation of primordial follicles. Granulosa cells of primordial and growing follicles, including medium-sized antral follicles also revealed SCF staining. In conclusion, this first report on SCF in human PGCs and embryonic and fetal ovaries together with the c-Kit data lend substantial countenance to the notion that c-Kit and SCF play important roles during ascent of primordial germ cells towards the gonadal anlage, and during oogenesis and folliculogenesis in the human fetal ovary. We suggest that both autocrine and paracrine mechanisms are involved in the proposed anti-apoptotic effect of the c-Kit/SCF duet while PGCs are present in the dorsal mesentery. The SCF-positive autonomic nerve fibers of the dorsal mesentery, mesothelial cells and fibroblasts may nurse and perhaps guide PGCs during their ascent.

The expression of stem cell factor and c-kit receptor in human asthmatic airways

BACKGROUND

Asthmatic airways are characterized by infiltration with a variety of inflammatory cells such as mast cells and eosinophils. Stem cell factor (SCF) is an important activating and chemotactic factor for both mast cells and eosinophils. In addition, it is a critical growth and differentiation factor for mast cells.

OBJECTIVES

To investigate the contribution of SCF to the pathogenesis of asthma, we examined the expression of SCF and its receptor c-kit in bronchial biopsies and bronchoalveolar lavage (BAL) specimens obtained from asthmatic subjects (n=13) and non-asthmatic control subjects (n=10).

METHODS

SCF and c-kit were detected by in situ hybridization (ISH) and immunocytochemistry (ICC). In order to phenotype the cells expressing SCF and c-kit in asthmatic tissue and BAL cells, combined ISH and ICC were also performed.

RESULTS

There was a significant difference (P<0.001) in the SCF mRNA expression in asthmatic airway epithelium (70.38+/-12.33% positive cells) compared with controls (12.7+/-17.21% positive cells). There was also a significant difference in subepithelial SCF-mRNA expression, being higher in asthmatics (P<0.001). A significant difference was also found in c-kit receptor mRNA expression in asthmatic biopsies both in epithelium (P<0.001) and subepithelium (P<0.05) compared with controls. ICC results were consistent with the ISH for both SCF and c-kit receptor from asthmatics and controls. The SCF and c-kit receptor mRNA and immunoreactivity in cells recovered from bronchial washing were also significantly higher in asthmatics compared with controls (P<0.05). While SCF expression was localized predominantly in the epithelial layer in bronchial biopsy tissues, alveolar macrophages were found to be the major source of SCF in bronchial washing from asthmatic subjects.

CONCLUSION

The results of this study demonstrate the increased expression of SCF and its receptor, c-kit within human asthmatic airways, which suggests an important role of this cytokine in the pathophysiology of asthma.

Relationship between cytokine concentrations (FGF, sICAM-1 and SCF) in serum, follicular fluid and ICSI outcome

OBJECTIVE

The aim of this study was (i) to investigate the existence of fibroblast growth factor (FGF), soluble intracellular adhesion molecule-1 (sICAM-1), and stem cell factor (SCF) in serum and human follicular fluid (FF) of intracytoplasmic sperm injection (ICSI) patients, and (ii) to determine the relationship between these parameters and ICSI outcome.

MATERIAL AND METHOD

Seventy-five patients undergoing controlled ovarian hyperstimulation with human menopausal gonadotropin (hMG) after down-regulation with GnRHa were included in this study. The concentrations of FGF, SCF, and sICAM-1 were measured by using commercially available enzyme-linked immunosorbent assay test kits.

RESULTS

The FGF, sICAM-1, and SCF concentrations in the serum of women who become pregnant (group I) were 8.5 +/- 1.5 pg/mL, 235.8 +/- 81.1 ng/mL, and 597.7 +/- 139.9 pg/mL, and the corresponding concentrations of women who did not (group II) were 6.4 +/- 3.6 pg/mL, 230.6 +/- 66.5 ng/mL, and 569.6 +/- 91.4 pg/mL respectively. No significant difference was observed between the two investigated groups with regard to the number of hMG ampoules administered for controlled ovarian hyperstimulation, estradiol concentration on the day of human chorionic gonadotropin (hCG) injection, number of retrieved oocytes and fertilization rate.

CONCLUSION

The concentration of FGF, sICAM-1, and SCF did not differ significantly between the two groups in serum or in FF. Besides, the ICSI outcome was not related to their concentrations in serum or FF. Therefore, these parameters could not be used as a prognostic factor in ICSI program.

[Expressions of bFGF, ET-1 and SCF in dermal papilla cells and the relation to their biological properties]

OBJECTIVE

To investigate the expression of bFGF, ET-1 and SCF in different passages of cultured dermal papilla cells (DPC), and their possible effect on biological behaviour of DPC.

METHODS

The expression of bFGF, ET-1 and SCF in different passages of cultured DPC was detected by immunocytochemistry and in situ hybridization.

RESULT

The expression of ET-1 and SCF in early passages of cultured DPC was stronger, but became negative in late passages (>6 passages). The stronger the expression of ET-1 and SCF in DPC, the higher ability of DPC to induce hair follicle regeneration.

CONCLUSION

The expression strength of ET-1 and SCF is related to the ability of DPC inducing hair follicle regeneration.

[Relationship between epithelial-immunologic cells transdifferentiation and pseudoepitheliomatous granuloma lesion]

OBJECTIVE

Inappropriate treatment at early stage of wound could result in the formation of pseudoepitheliomatous granuloma (PEG). The correlation of abnormal transdifferentiation of epithelial cells to immunologic cells and the occurrence of PEG lesion was investigated.

METHODS

Morphological change of epithelial tissue was observed with histopathology in 11 specimens of PEG lesions and 6 specimens of normal skins from PEG edge (PEG-N) from 11 patients with damaged skin. The expression characteristics and distribution of pan-cytokeratin (CKp), IV type collagen, laminin (LM), epithelial cadherin (E-Cad), beta-catenin (beta-Cat), focal adhesion kinase (FAK), stem cell factor (SCF) and its receptor-c-Kit, proliferating cell nuclear antigen(PCNA), and cluster of differentiation-14 (CD14), CD68 and mast cell tryptase (MCT) in PEG were detected with the immunohistochemical and the indirect immunofluorescent double-staining.

RESULTS

In comparison with PEG-N, epithelial tissue take on squamous metaplasia, and stroma was infiltrated with intensive microvessels and inflammatory cells in the PEG lesion. Poor epithelial basal layer constitution, basal polarization, and migration of basal cells to stroma could be observed. In the ultrastructure, the loose intercellular junction of basal cells and the increased nucleus/cytoplasm ratio and intercellular space could be observed, neonatal monocytoid cells and macrophages and mast cells as a exuviate-like manner brooded from cytoplasm of original epithelial cells and basement membrane. protein expression of CKp and E-Cad by basal cells was significantly decreased, and the IV type collagen and LM protein could not be found in basement membrane of identical locus. By contrast, the immunoreactivity of beta-Cat and FAK was apparently increased. In addition, CD14(+) monocytes, CD68(+) macrophages, MCT(+) mast cells and CD68(+)/MCT(+) cells with various size, and these cells of stronger immuno-staining of SCF, c-Kit and PCNA antigen could be found in epithelial tissue and stroma.

CONCLUSION

Epithelial cells in PEG related to wound are characteristized by transdifferentiation of epithelial cells to immunologic cells, wich may be associated with local infectious and inflammatory reaction, ultimately resulting in enhancement the ratio of beta-Cat/E-Cad signal and activation SCF-c-Kit signal pathway. The phenomena of transdifferentiation epithelial cells in the PEG lesion will help to recognize of the neoplatic immune and trauma repair mechanism.

Lack of KIT or FMS internal tandem duplications but co-expression with ligands in AML

KIT and FMS, members of the class III receptor tyrosine kinase family, are expressed on normal hematopoietic cells and have important roles in normal hematopoiesis. FLT3 is also a member of the class III receptor tyrosine kinase family and plays important role in hematopoietic stem/progenitor cells, NK, and dendritic cells. Recently, internal tandem duplication (ITDs) mutations have been found in the juxtamembrane (JM) region of FLT3 receptor expressed by patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). The mutations result in the constitutive dimerization and activation of the receptor, contributing to leukemic transformation. KIT and FMS are also frequently expressed in AML and are closely related to FLT3. Thus, similar ITD mutations could also occur in the KIT and/or FMS gene of patients with AML. To explore this possibility, 13 human leukemia-lymphoma cell lines and 44 AML patient samples were examined by reverse transcription-polymerase chain reaction (RT-PCR) for the presence of ITD mutations in the JM region of the KIT or FMS receptor. None of the 13 human leukemia-lymphoma cell lines or 44 AML primary bone marrow samples express ITDs in either KIT or FMS in the JM region that is involved in FLT3 mutations. The 13 cell lines and 44 AML samples were also examined for the possible co-expression of KIT and/or FMS receptors with their respective ligands, as we have seen for FLT3 and its ligand, FL. This co-expression could contribute to leukemic transformation through autocrine, paracrine, or intracrine activation mechanisms. And 6/13 cell lines and 27/44 primary AML samples exhibit co-expression of the KIT receptor and ligand (SCF) while 10/13 cell lines and 35/44 primary AML samples exhibit co-expression of the FMS receptor and ligand (CSF-1). Therefore, while ITD mutations were not found, the findings of co-expression of KIT and/or FMS with their respective ligands implies these receptors might contribute to leukemogenesis in some patients with AML through autocrine, paracrine, or intracrine interactive stimulation.

Kit is expressed by epithelial cells in vivo

In mammalian skin, stem cell factor (SCF) regulates the proliferation and maturation of mast cells and melanocytes, which are thought to be the only cutaneous cells that express the Kit-tyrosine kinase receptor (Kit) and respond to epithelial and mesenchymal-derived SCF. We previously had noted, however, the presence of Kit+ cells in murine hair follicles, in an introepithelial tissue compartment devoid of melanocytes and mast cells. Here we have identified the nature of this Kit+ population of cells in hair follicles of C57BL/6 mice. Anagen hair follicles showed strong Kit immunoreactivity not only in the pigmentary unit above the follicular dermal papilla but also in a much more proximally located, homogenous group of nondendritic, nonmelanized cells. By immunohistochemistry (desmoplakin+/Trp-1-) and electron microscopy (presence of tonofilaments, desmosomes, lack of melanosomes), these Kit+ cells were shown to be hair matrix keratinocytes and were also found in melanocyte-deficient hair follicles (Kit(Sl)/Kit(Sl-d) mice, Kit-neutralizing antibody-treated C57BL/6 mice). Expression of Kit and SCF was strongly hair-cycle-dependent, suggesting a functional role of epithelial Kit expression in hair growth control. This was supported by the observation that mice unable to respond to SCF stimulation (Kit(W)/Kit(W-v)) showed a significant retardation of anagen development compared to their wild-type littermates. The expression of Kit in the most rapidly proliferating compartment of the hair follicle epithelium suggests intriguing, as yet unexplored new functions of Kit signaling in epithelial cell biology.

Colony-Stimulating Activity of Fetal Liver Cells: Synergistic Role of Stem Cell Factor in Bone Marrow Recovery from Aplastic Anemia

Previously, we and others have shown that fetal liver infusion (FLI) leads to autologous hematopoietic improvement in 40-54% of patients with aplastic anemia. However, whether this recovery was spontaneous or the effect of the infused liver cells was not clear. To dissect the role of FLI in autologous hematopoietic recovery, the colony-supporting potential of fetal liver-conditioned medium (FLCM) was evaluated in bone marrow (BM) cells of normal adult and aplastic anemia patients. In both cases, each sample of FLCM supported the growth of colony-forming cells in semi solid culture medium. The FLCM was assayed for the presence of four principal colony-stimulating cytokines, namely stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and erythropoietin (Epo). While GM-CSF, IL-3, and Epo were present in insignificant amounts or were altogether absent, 50-635 pg/ml of SCF was found in 8 of the 13 FLCM samples tested. Preliminary results of bioneutralization assay indicated the possible role of SCF, secreted by the FL cells, in colony-supporting activity of aplastic anemia and normal BM cells. Overall, our in vitro study implicates the paracrine role of infused FL cells in regenerating autologous hematopoiesis in aplastic anemia patients.

Hmgb3: an HMG-box family member expressed in primitive hematopoietic cells that inhibits myeloid and B-cell differentiation

Hmgb3 is a member of a family of chromatin-binding proteins that can alter DNA structure to facilitate transcription factor binding. We identified the Hmgb3 cDNA in a subtractive hybridization screen for transcripts that are preferentially expressed in hematopoietic stem cells. We inserted an internal ribosomal entry site-green fluorescence protein cassette into the 3' untranslated region of the X-linked Hmgb3 locus to identify Hmgb3-expressing cells. In adult mice, Hmgb3 mRNA is detected in bone marrow cells, primitive Lin-, c-kit+, Sca-1+, IL-7Ralpha- cells, and Ter119+ erythroid cells. We observed that long-term repopulating ability is entirely contained in the subpopulation of Lin-, c-kitHI cells that express Hmgb3. Most common lymphoid and myeloid progenitors express Hmgb3. Introduction of a retrovirus containing the Hmgb3 cDNA into mouse bone marrow stem cells demonstrated that enforced expression of Hmgb3 inhibited B-cell and myeloid differentiation. We conclude that down-regulation of Hmgb3 protein levels is an important step for myeloid and B-cell differentiation.

Angiomyofibroblastoma of the vulva: report of a case with immunohistochemical and molecular analysis

A 43-year-old woman presented with a mass in the subcutaneous tissue of the right labium majus. A lipoma or Bartholin gland cyst was suspected and excision of the lesion was performed. The lesion was well circumscribed, and histological examination revealed a typical angiomyofibroblastoma. The lesion was composed of alternating hypocellular edematous and hypercellular areas with abundant vessels, and plump tumor cells were loosely dispersed or aggregated mainly around the vessels. Tumor cells were immunoreactive for vimentin and desmin but negative for muscle actins. Ultrastructurally, the tumor cells contained a moderate amount of rough endoplasmic reticulum and abundant intermediate filaments, and had primitive junctions. Pinocytotic vesicles or basal lamina were not evident. Immunohistochemical studies also revealed that the tumor cells expressed basic fibroblast-growth factor, vascular-endothelial-growth factor, and stem-cell factor, factors that may contribute to the rich vascularity and mast cells within the tumor. Reverse transcription-polymerase chain reaction detected high mobility group I-C (HMGI-C) transcripts in the tumor tissue. Because the expression of HMGI-C is regulated by developmental and differentiation processes and is not found in adult normal tissues, HMGI-C may be involved in the tumorigenesis of angiomyofibroblastoma.

Cell surface peptidase CD26/DPPIV mediates G-CSF mobilization of mouse progenitor cells

CXC ligand 12 (CXCL12; also known as stromal cell-derived factor 1alpha/SDF-1alpha) chemoattracts hematopoietic stem and progenitor cells (HSCs/HPCs) and is thought to play a crucial role in the mobilization of HSCs/HPCs from the bone marrow. CD26 (dipeptidylpeptidase IV [DPPIV]) is a membrane-bound extracellular peptidase that cleaves dipeptides from the N-terminus of polypeptide chains. CD26 has the ability to cleave CXCL12 at its position-2 proline. We found by flow cytometry that CD26 is expressed on a subpopulation of normal Sca-1+c-kit+lin- hematopoietic cells isolated from mouse bone marrow, as well as Sca-1+c-kit-lin- cells, and that these cells possess CD26 peptidase activity. To test the functional role of CD26 in CXCL12-mediated normal HSC/HPC migration, chemotaxis assays were performed. The CD26 truncated CXCL12(3-68) showed an inability to induce the migration of sorted Sca-1+c-kit+lin- or Sca-1+c-kit-lin- mouse marrow cells compared with the normal CXCL12. In addition, CXCL12(3-68) acts as an antagonist, resulting in the reduction of migratory response to normal CXCL12. Treatment of Sca-1+c-kit+lin- mouse marrow cells, and myeloid progenitors within this population, or Sca-1+c-kit-lin- cells with a specific CD26 inhibitor, enhanced the migratory response of these cells to CXCL12. Finally, to test for potential in vivo relevance of these in vitro observations, mice were treated with CD26 inhibitors during granulocyte colony-stimulating factor (G-CSF)-induced mobilization. This treatment resulted in a reduction in the number of progenitor cells in the periphery as compared with the G-CSF regimen alone. This suggests that a mechanism of action of G-CSF mobilization involves CD26.

Stem cell factor and crescentic glomerulonephritis

BACKGROUND

Numerous cells and cytokines have been implicated in the pathogenesis of crescentic glomerulonephritis (CGN). Recently, there has been growing awareness of the role of mast cells and their growth factor, stem cell factor (SCF), in the process of tissue inflammation and fibrosis.

METHODS

In this study, renal biopsy specimens from 28 patients with a histopathologic diagnosis of CGN were evaluated immunohistochemically for the presence of mast cells, SCF, and its receptor (c-kit). In addition, CD34+ hematopoietic cells, monocytes (CD68+ cells), and myofibroblasts (alpha-smooth muscle actin-positive [alpha-SMA+] cells) were counted. Renal biopsy specimens from cadaveric kidney donors and kidneys removed for hypernephroma (n = 6) served as controls. Point counting of positive immunostaining for SCF, alpha-SMA, and collagens III and IV was undertaken. Glomerular and interstitial fibrosis (IF) scores were determined.

RESULTS

Patients who developed progressive chronic kidney failure showed a significant increase in percentage of crescents, number of interstitial c-kit+ cells, and glomerular CD68+ cells compared with those with a favorable outcome. Analysis showed a significant elevation of tryptase+ mast cells in the interstitium of renal biopsy specimens of patients with CGN compared with controls. SCF and c-kit+ cells were found in glomeruli and interstitium, with occasional immunostaining of the crescent with SCF. Both glomerular and interstitial SCF immunostaining was significantly higher in biopsy specimens of patients compared with controls. Glomerular and interstitial SCF showed a significant positive correlation with 24-hour urinary protein level. There were a few CD34+ cells in both glomeruli and interstitium, but their numbers did not differ between patients and controls. Colocalization of CD34+ and c-kit+ was seen in some rounded interstitial and spindle-shaped cells. Number of interstitial mast cells proved to be a strong predictor of IF. Glomerular SCF correlated negatively with creatinine clearance and positively with glomerular CD68+ cells. Interstitial immunostainable SCF correlated positively with interstitial CD68+ cells and interstitial collagen III. On double antigen labeling, SCF was shown in the vicinity of alpha-SMA+ cells.

CONCLUSION

These results show the potential involvement of mast cells and their growth factor SCF/c-kit in CGN.

Decreased cutaneous expression of stem cell factor and of the p75NGF receptor in urticaria

BACKGROUND

Mast cells, the main effector cells in urticaria, have been reported to be increased in number in lesional and nonlesional skin of urticaria patients, but the underlying mechanisms have so far not been studied. Serum NGF has however, been reported to be increased in urticaria.

OBJECTIVES

We have therefore explored the potential involvement of known mast cell growth modulating factors in urticaria.

METHODS

Tissue sections from patients with different types of urticaria and healthy controls were studied for the immunohistochemical expression of known mast cell growth factors (stem cell factor, SCF; nerve growth factor, NGF), of the inhibitory granulocyte-macrophage colony-stimulating factor (GM-CSF), and of the corresponding receptors, using the alkaline phosphatase-antialkaline phosphatase technique.

RESULTS

Compared to skin of normal controls, staining for SCF, but not for NGF and GM-CSF, was significantly decreased in epidermis, endothelium and perivascular cells in lesional and nonlesional skin of all urticarias. On separate analysis of urticaria subtypes, decreased expression reached significance only in delayed pressure urticaria. Expression of the p75NGF receptor (p75NGFR) was also significantly decreased on endothelium and on perivascular cells of lesional and nonlesional skin in all urticarias. On evaluation of serial sections, p75NGFR expression was also decreased on c-Kit positive dermal mast cells. In contrast, expression of the NGF receptor tyrosine kinase and of the SCF and GM-CSF receptors was unchanged.

CONCLUSIONS

These findings show that SCF and p75NGFR are selectively and systemically down-regulated in the skin of urticaria patients and may represent a negative feedback to increased mast cell reactivity and proliferation.

The stem cell factor-c-kit system and mast cells in human pancreatic cancer

Stem cell factor (SCF) and its receptor c-kit take part in the regulation of developmental processes of mast cells, hematopoietic stem cells, and melanocytes, as well as in the growth control of human malignancies. To explore the possible role of the SCF-c-kit system and of mast cells in pancreatic cancer, the concomitant expression and distribution of the two molecules were examined in 17 normal and 26 cancerous human pancreatic tissues and in 6 cultured pancreatic cancer cell lines. Mast cell distribution was also evaluated in the same tissue samples. In addition, the effects of SCF and of the c-kit tyrosine-kinase inhibitor STI571 on the growth of the cancer cell lines and of the normal pancreatic ductal cell line TAKA-1 were assessed. SCF immunoreactivity was absent in acinar, ductal, and islet cells of the normal pancreas and faint in pancreatic cancer tissues and cell lines. In contrast, c-kit was clearly present in some normal and hyperplastic ducts of the normal pancreas, in the cancer cells of 73% of the tumor samples, and in all the cell lines tested. Mast cells, identified by tryptase and chymase immunostaining on consecutive tissue sections, showed immunoreactivity for SCF and c-kit in both normal and cancerous specimens and their number was significantly increased (p = 0.03) in pancreatic cancer compared with the normal pancreas. SCF showed a dose-dependent growth inhibitory effect on TAKA-1 cells (p < 0.001), whereas pancreatic cancer cells were resistant to the SCF-induced growth inhibition. Nonetheless, the growth of TAKA-1 cells and pancreatic cancer cells was inhibited by the c-kit tyrosine kinase inhibitor STI571. In conclusion, the SCF-c-kit system, possibly with the contribution of mast cells, may have a growth-regulating role in the normal pancreas, which is altered during malignant transformation.

Vasoactive intestinal peptide and cytokines enhance stem cell factor production from epidermal keratinocytes DJM-1

Stem cell factor can induce mast cell proliferation and melanocyte activation. Vasoactive intestinal peptide has been suggested to play a part in inflammatory dermatoses, such as atopic dermatitis. The aim of this study was to investigate the possible role of stem cell factor in atopic dermatitis by analyzing epidermal stem cell factor production induced by vasoactive intestinal peptide and cytokines. Full-length type stem cell factor transcript was detected in normal human epidermal keratinocytes, and a human epidermal keratinocyte cell line DJM-1, as well as normal human dermal fibroblasts, using reverse transcription-polymerase chain reaction. Spliced-type stem cell factor transcript was detected in both DJM-1 cells and normal human epidermal keratinocytes. Western blot analysis with stem cell factor antibody revealed a protein of the known molecular size of membrane-bound stem cell factor in the lysates of all three cell types. Stem cell factor immunoreactivity was found in the cytoplasm and the membrane of both DJM-1 cells and normal human epidermal keratinocytes using confocal laser scanning microscope. We examined the effects of vasoactive intestinal peptide and cytokines on stem cell factor production of DJM-1 cells using enzyme-linked immunosorbent assays. Stem cell factor contents significantly increased in culture supernatants of DJM-1 cells treated with 1000 nm vasoactive intestinal peptide and/or cytokines, including interleukins 4 and 13, tumor necrosis factor-alpha, and interferon-gamma. Overall, these results suggest that several inflammatory cytokines (T helper 1 and 2) and vasoactive intestinal peptide from mast cells and nerve endings are capable of inducing stem cell factor production from epidermal keratinocytes in atopic dermatitis.

Hodgkin and Reed-Sternberg cells express functional c-kit receptors and interact with primary fibroblasts from Hodgkin's disease-involved lymph nodes through soluble and membrane-bound stem cell factor

Classic Hodgkin's disease (cHD) is a lymphoid neoplasia characterized by few malignant Hodgkin and Reed-Sternberg (H-RS) cells, embedded in an abundant background of non-tumour cells. We have previously demonstrated the expression in primary H-RS cells of the receptor tyrosine kinase (RTK) c-kit; here we describe its functional role in the cross-talk between H-RS cells themselves with neighbouring cell populations. In particular, we analysed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of HD-derived cell lines and fibroblasts from HD-involved lymph nodes (HDF). While c-kit was expressed by HD-derived cell lines, usually in the absence of SCF, this latter molecule, in its soluble and/or membrane-bound (mb) form, was in turn expressed at a high level by primary HDF. In vitro adhesion between HD-derived cell lines and HDF was mainly mediated by c-kit/SCF interactions, and this phenomenon was significantly inhibited by an excess of soluble SCF or by neutralizing anti-c-kit monoclonal antibodies. Furthermore, both soluble and mb-SCF increased growth and colony survival of HD-derived cell lines; these effects were significantly enhanced upon co-stimulation of H-RS cells with interleukin 9. Finally, soluble SCF was able to partially rescue H-RS cells from apoptosis induced by serum starvation. Taken together, our data indicated the expression of functional c-kit receptor by H-RS cells and suggests a role of SCF in the pathobiology of cHD.

Zinc-finger transcription factor Slug contributes to the function of the stem cell factor c-kit signaling pathway

The stem cell factor c-kit signaling pathway (SCF/c-kit) has been previously implicated in normal hematopoiesis, melanogenesis, and gametogenesis through the formation and migration of c-kit(+) cells. These biologic functions are also determinants in epithelial-mesenchymal transitions during embryonic development governed by the Snail family of transcription factors. Here we show that the activation of c-kit by SCF specifically induces the expression of Slug, a Snail family member. Slug mutant mice have a cell-intrinsic defect with pigment deficiency, gonadal defect, and impairment of hematopoiesis. Kit(+) cells derived from Slug mutant mice exhibit migratory defects similar to those of c-kit(+) cells derived from SCF and c-kit mutant mice. Endogenous Slug is expressed in migratory c-kit(+) cells purified from control mice but is not present in c-kit(+) cells derived from SCF mutant mice or in bone marrow cells from W/W(v) mice, though Slug is present in spleen c-kit(+) cells of W/W(v) (mutants expressing c-kit with reduced surface expression and activity). SCF-induced migration was affected in primary c-kit(+) cells purified from Slug-/- mice, providing evidence for a role of Slug in the acquisition of c-kit(+) cells with ability to migrate. Slug may thus be considered a molecular target that contributes to the biologic specificity to the SCF/c-kit signaling pathway, opening up new avenues for stem cell mobilization.

[Hematopoietic cytokines as tumor markers]

Serum tumour markers may be helpful in early diagnosis of cancer, in the initial assessment of the extent of the disease, and in monitoring of the tumour growth or tumour volume reduction, once cancer has been diagnosed and treatment started. Recent studies have focused on a new family of markers--hematopoietic cytokines.

Levels of mast-cell growth factors in plasma and in suction skin blister fluid in adults with mastocytosis: correlation with dermal mast-cell numbers and mast-cell tryptase

BACKGROUND

Mast-cell accumulation has been observed in the skin and other organs of patients with systemic indolent mastocytosis (SM). The basis for this pathologic increase is not fully understood.

OBJECTIVE

We sought to determine levels of mast-cell growth factors in the skin and plasma of patients with SM, patients with atopic dermatitis (AD), and healthy individuals and to correlate these levels to dermal mast-cell numbers and levels of mast-cell tryptase.

METHODS

Skin suction blister fluid and plasma levels of stem-cell factor, IL-3, IL-4, IL-6, vascular endothelial growth factor, and total mast-cell tryptase were analyzed by means of ELISA. The number of mast cells was determined in a biopsy section taken from adjacent skin.

RESULTS

Mast-cell numbers in the dermis were higher in patients with SM compared with numbers in patients with AD (P <.001) or in healthy control subjects (P <.0001) and correlated with tryptase levels in both skin blister fluid (P <.0001) and plasma (P <.0001). Stem-cell factor and vascular endothelial growth factor levels in the skin blister fluid and plasma of patients with SM were not significantly different from those in patients with AD or healthy control subjects. IL-3 and IL-4 levels were below the limit of detection. IL-6 levels were significantly increased in the plasma of patients with SM compared with in plasma of patients with AD (P <.002) and healthy control subjects (P <.0001) and correlated with plasma tryptase levels (P <.05) and dermal mast-cell numbers (P <.02).

CONCLUSION

Because elevated levels of IL-6 could contribute to the fever, fatigue, and osteoporosis observed in patients with SM and because IL-6 is antiapoptotic for mast cells, IL-6 could potentiate the biologic consequences of this disease.

Mast cell distribution and activation in chronic pancreatitis

Chronic pancreatitis (CP) is characterized by mononuclear inflammatory cell infiltration and replacement of the destroyed parenchyma by fibrous tissue. Recently, mast cells have been implicated in chronic inflammatory processes with fibrous tissue deposition. Therefore, the number and distribution of mast cells and their state of activation were evaluated in 12 normal specimens and in 46 specimens of CP with different causes (alcoholic, tropical, and idiopathic). Furthermore, the presence of stem cell factor (SCF), the main mast cell growth factor, and of its receptor, c-kit, was also assessed. In CP tissues, mast cells were localized both in the fibrotic areas and in the residual acinar parenchyma. The total number of mast cells was significantly higher in CP than in the normal pancreas (P < .0001) and correlated positively with the extent of fibrosis and the intensity of inflammation. Immunoglobulin E (IgE)-dependent mast cell activation was higher in CP than in the normal pancreas. No differences in mast cell number or IgE positivity were found among the 3 causes of CP. SCF-and c-kit immunoreactive mast cells were mostly localized in fibrous tissue and around regenerating ducts, which were also positive for c-kit but were negative for SCF. These results suggest that mast cells, activated by an IgE-dependent mechanism and/or by an SCF-c-kit autocrine loop, are a relevant component of the inflammatory infiltrate in CP, independent of the underlying cause. Their localization near degenerating acini and regenerating ducts might indicate that they play a crucial role in tissue destruction and remodeling in CP.

Demonstration of mast cell chemotactic activity in synovial fluid from rheumatoid patients

OBJECTIVES

The significance of the mast cell in the pathogenesis of rheumatic diseases has become more evident. Although mast cell hyperplasia is a feature of rheumatoid arthritis, the nature of mast cell chemoattractants involved in the recruitment of mast cells in joint diseases has not been studied in any detail. In this study the presence of mast cell chemotactic activity in synovial fluids was examined.

METHODS

Synovial fluids from seven rheumatoid patients were tested in a modified Boyden chamber, where a human mast cell line was used as responder. The presence of stem cell factor (SCF) and transforming growth factor beta (TGFbeta) was measured by enzyme linked immunosorbent assay (ELISA).

RESULTS

Six of the seven synovial fluids tested exhibited mast cell chemotactic activity. Two characterised human mast cell chemotaxins, SCF and TGFbeta, were highly expressed in the synovium. Soluble SCF could be detected in all fluids analysed. Blocking antibodies against SCF or TGFbeta almost completely blocked the activity in one fluid, partially blocked the activity in three, and did not affect the activity in two. Treatment of the responder cells with pertussis toxin reduced the migratory response against seven fluids, indicating the presence of chemoattractants mediating their effect through G(i) coupled receptors.

CONCLUSION

These data demonstrate the presence of multiple factors in synovial fluid acting as mast cell chemoattractants, two of which are SCF and TGFbeta that contribute to the effect. These findings may be of importance for developing new strategies to inhibit mast cell accumulation in rheumatic diseases.

Interleukin-6 and the soluble interleukin-6 receptor induce stem cell factor and Flt-3L expression in vivo and in vitro

OBJECTIVE

We recently established transgenic animals expressing either interleukin-6 (IL-6) or the soluble IL-6 receptor (sIL-6R) alone, or both components, IL-6 and the sIL-6R, in the liver. This animal model demonstrated that the expression of IL-6 in combination with its sIL-6R led to extramedullary expansion of hematopoietic progenitor cells in the spleen and liver.

MATERIALS AND METHODS

We studied other relevant hematopoietic cytokines involved in the IL-6/sIL-6R-induced stimulation of hematopoiesis.

RESULTS

Using immunohistochemistry, we showed that cell-associated stem cell factor (SCF) and Flt-3L expression were upregulated in liver and spleen only in double transgenic mice but not in IL-6 or sIL-6R single transgenic animals. Moreover, on murine NIH/3T3 fibroblasts and on human primary forskin fibroblasts, stimulation with the IL-6/sIL-6R complex, and to a lesser extent with IL-6 alone, led to induction of cellular SCF and Flt-3L expression. When human HTB-158 fibroblasts were stimulated with the IL-6/sIL-6R complex and subsequently cocultured with human umbilical cord CD34(+) cells, a significant upregulation in colony growth was found.

CONCLUSIONS

We showed that IL-6 in combination with its soluble receptor stimulates cellular SCF and Flt-3L expression in vivo and in vitro. Cellular upregulation of SCF and Flt-3L by IL-6/sIL-6R might be used for the development of new stroma cell systems for ex vivo expansion of hematopoietic progenitor cells.

Possible contribution of stem cell factor in psoriasis vulgaris

It is suggested that mast cell is implicated to play a role in the pathogenesis of psoriasis. In this study, to determine the role of stem cell factor (SCF), which is a growth factor of mast cells, we have examined the immunohistochemical localization and serum level of SCF in patients with psoriasis vulgaris. Immunohistochemical analysis revealed diffuse staining for SCF on keratinocytes in acanthotic epidermis in psoriasis, along with endothelial cells and fibroblasts. Serum SCF level, which was measured by enzyme-linked immunosorbent assay (ELISA), was significantly increased in patients with psoriasis vulgaris (1033+/-334 pg/ml) (n=24) than that of normal subjects (666+/-196 pg/ml) (n=15) (P<0.05). However, serum SCF did not show a correlation with the disease severity assessed by psoriasis activity and severity index (PASI) score. As patients with psoriasis vulgaris occasionally complain itching, next we divided 20 patients into two groups, those with itching (Group I) (n=8) and those without (Group II) (n=12), and compared the mast cell number located in the papillary dermis between thickened psoriatic epidermis, serum SCF and plasma histamine levels. Results showed that mast cell numbers (56.3+/-22.3/mm(2) in Group I vs 31.5+/-10. 3/mm(2) in Group II, P<0.05) and plasma histamine level (1.5+/-0.59 ng/ml vs 0.39+/-0.15 ng/ml, P<0.01) were significantly higher in patients of Group I than those of patients of Group II, however, the difference of serum SCF level (1132+/-368 pg/ml vs 890+/-373 pg/ml) did not reach a statistical significance. Finally, in a separate experiment, we examined whether exogenous SCF is capable of inducing psoriatic architecture on the transplanted uninvolved psoriatic skin onto severe combined immunodeficient (SCID) mice. SCF injection for 2 weeks could not induce a psoriasiform architecture such as acanthosis on the transplanted uninvolved psoriatic skin, although mast cells were increased in number. These results raised a possibility that keratinocyte-derived SCF plays a role, in part, in the increased number of mast cells in the papillary dermis of psoriasis, which may lead pruritus associated with psoriasis. Elevated serum SCF level may also be responsible for increment of mast cells in psoriasis vulgaris. Mast cell-derived factor stimulated by exogenous SCF could not induce psoriatic epidermis, suggesting that other factors such as activated lymphocytes or macrophages are further required for the development of psoriatic lesions.

Detection and quantitation of stem cell factor (kit ligand) in the synovial fluid of patients with rheumatic disease

OBJECTIVE

To identify and quantitate stem cell factor (SCF; kit ligand) in the serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA) and to compare these values with those measured in normal serum, RA serum, SF of patients with other rheumatic diseases, and conditioned medium from cultured synoviocytes.

METHODS

SCF was measured in serum, SF, and conditioned synovial cell culture medium by a sensitive ELISA. Results were correlated with hematologic variables including white blood cell count, hemoglobin, platelet count, erythrocyte sedimentation rate, and rheumatoid factor.

RESULTS

SCF levels in RA SF exceeded those measured in RA serum, osteoarthritis SF, and SF from patients with other inflammatory arthropathies. SCF was detectable in conditioned medium from cultured synoviocytes.

CONCLUSION

High levels of SCF are present in RA serum and SF. Local production of SF may influence expansion of myeloid progenitor cells and mast cell function in RA.