Comprehensive flow cytometric reference intervals of leukocyte subsets from six study centers across Europe

A group of European FOCIS Centers of Excellence adapted panels of the Human Immunophenotyping Consortium (HIPC) for whole blood analysis. Using four core panels [T/regulatory T cell/B/natural killer (T/T_reg/B/NK) and myeloid cells] the main leukocyte populations were analyzed in a clinical–diagnostic setting in a harmonized manner across different platforms. As a first step, the consortium presents here the absolute and relative frequencies of the leukocyte subpopulations in the peripheral blood of more than 300 healthy volunteers across six different European centers.

A study of 51 subtypes of peripheral blood immune cells in newly diagnosed young type 1 diabetes patients

Type 1 diabetes (T1D) results from autoimmune destruction of insulin-producing beta cells in pancreatic islets. Various immune cell populations are involved in disease development and natural course. However, to our knowledge, so far there are no comprehensive comparative investigations of all main immune cell populations and their most important subsets at the onset of disease. Therefore, in the current study, we analyzed 51 peripheral blood immune cell populations in 22 young T1D patients and in 25 age-matched controls using a comprehensive polychromatic flow cytometry panel developed for whole blood by the COST Action no. BM0907 ENTIRE (European Network for Translational Immunology Research and Education: From Immunomonitoring to Personalized Immunotherapy) consortium. We found that in T1D patients, frequencies and absolute counts of natural killer (NK) cells, dendritic cells (DC) and T cells, as well as their respective subsets, were significantly altered compared to controls. Further, we observed that changes in several cell populations (e.g. CD14⁺ CD16⁺ non-classical monocytes, plasmablasts) were dependent on the age of the patient. In addition to age-related changes, we also found that alterations in immune cell patterns were associated with parameters such as the presence of ketoacidosis and C-peptide serum levels. Our study provides a foundation for future studies investigating different cell lineages and their role in T1D and illustrates the value of polychromatic flow cytometry for evaluating all main peripheral immune cells and their subsets in whole blood samples.

Blood immune cell biomarkers in lung cancer

Characterization of host immune cell parameters prior to treatment is expected to identify biomarkers predictive of clinical outcome as well as to elucidate why some patients fail to respond to immunotherapy. We monitored blood immune cells from 58 patients with non-small- cell lung cancer (NSCLC) undergoing surgery of the primary tumor and from 50 age-matched healthy volunteers. Complete leukocyte blood count, the number of circulating dendritic cells (DC), HLA-DR^low monocytes and several lymphocytic subpopulations were determined by eight-color flow cytometry. Furthermore, the prognostic value of the immune cell parameters investigated was evaluated by patients' survival analysis. Compared to the control group, blood of NSCLC patients contained more neutrophils resulting in a higher neutrophil-to-lymphocyte ratio (NLR), but a lower number of blood DC, in particular of plasmacytoid DC (pDC), natural killer (NK) cells and naive CD4⁺ and CD8⁺ T cells. Furthermore, a higher frequency of CD4⁺ regulatory T cells (Treg) and HLA-DR^low monocytes was detected, and smoking had a significant impact on these values. HLA-DR^low monocytes were positively correlated to the number of neutrophils, monocytes and NLR, but negatively associated with the number of pDC and naive CD4⁺ T cells. The frequency of Treg, HLA-DR^low monocytes and naive CD4⁺ and CD8⁺ T cells as well as the ratios of CD4/HLA-DR^low monocytes and HLA-DR^low monocytes/pDC correlated with patient's overall survival. Next to Treg, HLA-DR^low monocytes and naive T cells represent prognostic markers for NSCLC patients and might be useful for monitoring of patients' responses to immunotherapies in future studies.

Reduced residual gene expression of nuclear factor of activated T cells-regulated genes correlates with the risk of cytomegalovirus infection after liver transplantation

BACKGROUND

Pharmacokinetic monitoring of calcineurin inhibitors (CNIs) is unsatisfactory because, at comparable blood concentrations, side effects vary considerably. We recently confirmed the applicability of a pharmacodynamic (PD) assay that measures the suppression of CNI target genes, specifically the suppression of nuclear factor of activated T cells (NFAT)-regulated genes in liver transplant (LT) recipients. The aim of this prospective study was to prove the clinical reliability of this assay. Therefore, we quantified the residual gene expression (RGE) of NFAT-regulated genes and evaluated the association between the RGE of NFAT-regulated genes and the incidence of cytomegalovirus (CMV) infection.

PATIENTS AND METHODS

In 20 LT recipients, 10 patients on cyclosporine (CsA) and 10 patients on tacrolimus (Tac) therapy, who presented with CMV infection, the RGEs of interleukin-2, interferon-γ (IFNγ), and granulocyte-monocyte colony-stimulating factor were measured and compared with the RGEs of these cytokines in 40 healthy dose-matched LT controls.

RESULTS

CsA-treated CMV patients demonstrated a lower RGE of all NFAT-regulated genes compared with controls (30 ± 17 vs. 44 ± 20, P = 0.067). For IFNγ, the level of significance was reached (26 ± 17 vs. 43 ± 17, P = 0.0125). Daily CsA dosage, CsA baseline (C0 ) and 2 h (C2 ) concentrations were comparable (CsA dosage 169 mg/day vs. 165 mg/day; CsA C0 94 μg/L vs. 85 μg/L; CsA C2 389 μg/L vs. 381 μg/L). In addition, Tac-treated CMV patients demonstrated a lower RGE of all NFAT-regulated genes compared with controls (68 ± 25 vs. 84 ± 22, P = 0.0769). Analogous to CsA-treated CMV patients, the level of significance was reached for IFNγ (61 ± 24 vs. 88 ± 29, P = 0.0154). Daily Tac dosage and Tac 1.5 h concentrations (C1.5 ) were comparable in both groups (Tac dosage 4 mg/day vs. 4 mg/day; Tac C1.5 8 μg/L vs. 10 μg/L), whereas Tac C0 concentrations were significantly higher in controls (Tac C0 4 μg/L vs. 6 μg/L, P = 0.0276).

CONCLUSION

Measuring the RGE of NFAT-regulated genes is appropriate to assess the risk of infections in LT recipients. Measuring the RGE of IFNγ is particularly suitable to assess the risk of CMV infection. PD monitoring of CNIs in LT recipients is an approach to individualize immunosuppression, which may help to reduce infectious complications.

Osteoclast Generation and Cytokine Profile at Prosthetic Interfaces: A Study on Tissue of Patients with Aseptic Loosening or Implant-Associated Infections

Aseptic loosening of implants or loosening due to persistent bacterial infection remains a severe complication in orthopaedic surgery. To investigate underlying cellular and molecular mechanisms, particularly with regard to bone loss, tissue samples of patients requiring surgery were examined. By histological methods and by quantitative RT-PCR, respectively, infiltration of leukocytes, expression of osteoclast-typical genes and of proinflammatory cytokines was determined. Samples were taken directly from osteolytic sites and for comparison from adjacent sites, distant sites and from muscle. At osteolytic sites, cathepsin K and the metalloproteinases MMP1 and MMP9 were found, as was expression of inflammation-related cytokines, particularly of interleukin (IL)-1β, CXCL8, S100A9 and a very moderate expression of receptor activator of NfκB ligand (RANKL) and tumour necrosis factor (TNF) a. Of note, expression of these parameters gradually decreased from sites of osteolysis to adjacent tissue, to distant tissue to muscle. In patients with infection and osteolysis, expression of cytokines, notably of CXCL8, was markedly enhanced, especially in adjacent and distant tissues, where expression was 10- to 20-fold higher compared to tissue of aseptic patients. A possible source of CXCL8 could be infiltrated cells, particularly neutrophils, because they were found in infected tissue only. Histological examination of the biopsies revealed an additional CXCL8 source, namely endothelial cells of small blood vessels. In conclusion, aseptic loosening and implant-associated infection are associated with osteoclast generation and a local inflammatory response. The proinflammatory environment could promote the differentiation of precursor cells to osteoclasts, thereby linking inflammation to bone resorption. The higher expression of cytokines, particularly of CXCL8 in tissue of patients with bacterial infection, could explain the accelerated time course of bone resorption as it occurs in infection compared to aseptic loosening.

The novel c-Met inhibitor cabozantinib overcomes gemcitabine resistance and stem cell signaling in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal malignancies. Cancer stem cells (CSCs), which are not targeted by current therapies, may be the reason for pronounced therapy resistance. A new treatment option in phase II trials is cabozantinib that inhibits the pancreatic CSC surface marker and tyrosine kinase receptor c-Met. The purpose of this study was to evaluate the effect of cabozantinib to stem-like features and therapy resistance. Established PDA cell lines, a gemcitabine-resistant subclone, non-malignant pancreatic ductal cells and primary spheroidal cultures from patient tumors were analyzed by MTT-assay, flow cytometry, colony and spheroid formation assays, western blotting, qRT-PCR, antibody protein array, immunohistochemistry and morphological features. Cabozantinib inhibited viability and spheroid formation and induced apoptosis in malignant cells with minor effects in non-malignant cells. After long-term cabozantinib treatment, PDA cells had altered anti- and pro-apoptotic signaling, but still responded to cabozantinib, as apoptosis only slightly decreased and viability only slightly increased suggesting a low resistance-inducing potential of cabozantinib. In parallel, c-Met expression and the pluripotency transcription factor SOX2 were downregulated, which might counteract development of full therapy resistance in long-term treated subclones. In single-treatment studies, cabozantinib increased efficacy of gemcitabine. Most importantly, cabozantinib strongly induced apoptosis and reduced viability in PDA cell lines, which are completely resistant toward gemcitabine. In primary, CSC-enriched spheroidal cultures cabozantinib downregulated CSC markers SOX2, c-Met and CD133 and induced apoptosis. These findings suggest that the clinical use of cabozantinib may be more effective than current chemotherapeutics.

Human mucosal CD4+ T cells but not blood CD4+ T cells respond vigorously towards CD28 engagement

Human lamina propria T lymphocytes (LPT) possess functional properties profoundly different from those of peripheral blood T lymphocytes (PBT). While they are characterized by a low proliferative response to T cell receptor (TCR)/CD3 stimulation in vitro their responsiveness to activation through the 'co-stimulatory' CD2-receptor is enhanced when compared to PBT. In this study, we demonstrate that engagement of another co-stimulatory receptor on both LPT and PBT, namely CD28, by a single monoclonal antibody (mAb), respectively, strongly activates the former but not the latter through a PI3-kinase dependent signalling pathway leading to the production of inflammatory cytokines such as interleukin (IL)-2, tumour necrosis factor (TNF)-α, interferon (IFN)-γ and granulocyte-macrophage colony-stimulating factor (GM-CSF). In addition to the high sensitivity of LPT to CD2 stimulation, this finding supports the notion that 'non-specific/innate' mechanisms to activate T lymphocytes play a predominant role vis-à-vis'TCR driven/adaptive' responses in the intestinal mucosa. Furthermore, it suggests that results from preclinical tests for therapeutic antibodies performed with human blood derived T cells are probably insufficient to predict reactivities of tissue-resident immune cells, which--given their quantitative predominance--may critically determine the in-vivo response to such compounds.

Immunogenicity of SEREX-identified antigens and disease outcome in pancreatic cancer

Despite spontaneous or vaccination-induced immune responses, pancreatic cancer remains one of the most deadly immunotherapy-resistant malignancies. We sought to comprehend the spectrum of pancreatic tumor-associated antigens (pTAAs) and to assess the clinical relevance of their immunogenicity. An autologous SEREX-based screening of a cDNA library constructed from a pancreatic T3N0M0/GIII specimen belonging to a long-term survivor (36 months) revealed 18 immunogenic pTAA. RT-PCR analysis displayed broad distribution of the identified antigens among normal human tissues. PNLIPRP2 and MIA demonstrated the most distinct pancreatic cancer-specific patterns. ELISA-based screening of sera for corresponding autoantibodies revealed that although significantly increased, the immunogenicity of these molecules was not a common feature in pancreatic cancer. QRT-PCR and immunohistochemistry characterized PNLIPRP2 as a robust acinar cell-specific marker whose decreased expression mirrored the disappearance of parenchyma in the diseased organ, but was not related to the presence of PNLIPRP2 autoantibodies. Analyses of MIA-known to be preferentially expressed in malignant cells-surprisingly revealed an inverse correlation between intratumoral gene expression and the emergence of autoantibodies. MIA(high) patients were autoantibody-negative and had shorter median survival when compared with autoantibody-positive MIA(low) patients (12 vs. 34 months). The observed pTAA spectrum comprised molecules associated with acinar, stromal and malignant structures, thus presenting novel targets for tumor cell-specific therapies as well as for approaches based on the bystander effects. Applying the concept of cancer immunoediting to interpret relationships between gene expression, antitumor immune responses, and clinical outcome might better discriminate between past and ongoing immune responses, consequently enabling prognostic stratification of patients and individual adjustment of immunotherapy.

TNF-alpha antibody treatment in refractory collagenous sprue: report of a case and review of the literature

Collagenous sprue (CS) is a rare disease characterized by celiac type small bowel malabsorption that is resistant to gluten free diet (GFD) and is associated with a poor prognosis. Our aim was to assess the properties of the monoclonal TNF-alpha antibody infliximab in a patient with high-dose steroid refractory CS. A 27-year-old man developed watery diarrhea with weight loss and abdominal pain. Duodenal biopsies showed a subtotal villous atrophy with an extensive subepithelial layer of collagenous fibers. An apparent GFD did not reduce symptoms. High dose steroid treatment (75 mg prednisone) in combination with azathioprine (150 mg) reduced diarrhea but did not induce complete remission. Based on strongly elevated mucosal TNF-alpha transcript concentrations we introduced infliximab (5 mg/kg body weight) into therapy. After two applications the patient's symptoms quickly improved. During the following year no recurrence of diarrhea has been observed. This case suggests that infliximab is an effective treatment in complicated cases of collagenous sprue.

Abnormal crosstalk between pancreatic acini and macrophages during the clearance of apoptotic cells in chronic pancreatitis

In chronic pancreatitis (CP), both the progressive loss of acinar parenchyma and aggressive fibro-inflammatory reactions ultimately lead to irreversible organ destruction. Dying cells are normally removed by macrophages and elimination is associated with anti-inflammatory cytokine switch. We investigated whether defective clearance of damaged acini by macrophages such as compromised phagocytosis or altered cytokine reaction occurs in CP and thus represents a causative link between acinar loss and fibro-inflammation. In a checkerboard-like co-culture system, we assessed normal and CP macrophages for their phagocytic and cytokine responses to dying pancreatic acinar cells of normal or CP origin by FACS, confocal microscopy, QRT-PCR, and ELISA. In CP, phagocytosis of apoptotic acini by macrophages was not impaired; however, the associated cytokine responses were gradually perturbed. Most interestingly, only normal acini suppressed TGFbeta1 expression and accumulation specifically in normal macrophage cultures, while CP acini lost this ability. Both types of apoptotic acini induced pro-inflammatory cytokine bursts of varying strength in both types of macrophages; however, the most significant difference (more than 50-fold higher expression of IL-1beta, IL-6, and IL-8) was evident between CP/CP and normal/normal combinations, indicating that acinar and macrophage alterations synergistically lead to the ultimate CP-specific bias. In combination with in situ data comparing circulating inflammatory cells to pancreatic resident ones, our results indicate that cytokine expression in inflammatory cells undergoes spatiotemporal modulation, most likely through a successive interplay of acinar, stromal, and circulating factors. Thus, clearance of injured pancreatic acini by macrophages is associated with a unique cytokine reaction which may constitute a basis for progression of SAPE (sentinel acute pancreatitis event) to the irreversible fibro-inflammation in CP.

Up-regulation of the phosphoinositide 3-kinase pathway in human lamina propria T lymphocytes

Human intestinal lamina propria T lymphocytes (LPT), when investigated ex vivo, exhibit functional properties profoundly different from those of peripheral blood T lymphocytes (PBT). One prominent feature represents their enhanced sensitivity to CD2 stimulation when compared to PBT. Given that LPT are hyporesponsive to T cell receptor (TCR)/CD3 stimulation, an alternative activation mode, as mimicked by CD2 triggering in vitro, may be functional in mucosal inflammation in vivo. This study provides insight into signalling events associated with the high CD2 responsiveness of LPT. When compared to PBT, LPT show an increased activation of the phosphoinositide 3/protein kinase B/glycogen synthase kinase 3beta (PI3-kinase/AKT/GSK-3beta) pathway in response to CD2 stimulation. Evidence is provided that up-regulation of this pathway contributes to the enhanced CD2-induced cytokine production in LPT. Given the importance of TCR-independent stimulation for the initiation of intestinal immune responses analysis of signalling pathways induced by 'co-stimulatory' receptors may provide valuable information for therapeutic drug design.

Association between suppressors of cytokine signalling, T-helper type 1/T-helper type 2 balance and allergic sensitization in children

BACKGROUND

Suppressors of cytokine signalling (SOCS) family members have been shown to play an important role in the balance of cytokines that determine the onset of T-helper type 1 (Th1)- and Th2-mediated immune responses. In particular, for cytokine-induced Src-homology 2 protein (CIS), SOCS1, SOCS3 and SOCS5, a role in the regulation of T cell differentiation has been discussed. However, only few data exist so far in the human system.

OBJECTIVES

The aim of the present study was to analyse the relationship between these suppressors and Th1/Th2 regulation as well as allergic sensitizations within a population-based study.

METHODS

Within the Lifestyle-Immune system-Allergy plus cohort study, mRNA was prepared from blood samples of 6-year-old children for the analysis of cytokines, transcription factors for T cell regulation and SOCS molecule expression by quantitative real-time polymerase chain reaction. In addition, total and specific IgE concentrations have been measured by the Pharmacia CAP System. A complete data set from 248 children was available. Results Among the SOCS molecules investigated, only SOCS1 showed a strong positive correlation to allergic sensitizations. In addition, an up-regulated SOCS1 expression correlated with down-regulated T-box expressed in T cells (Tbet) and higher expression levels of GATA-binding protein 3 (GATA-3) and IL-4. No association between SOCS1 and forkhead box P3 (FOXP3) was observed. For SOCS3, SOCS5 and CIS, a contradictory picture was found. The expression of these SOCS molecules was positively correlated with Tbet and FOXP3 and (with the exception of CIS) negatively with IL-4.

CONCLUSIONS

Our data suggest that SOCS3, SOCS5 and CIS, which correlate with an up-regulated Th1 and regulatory T cell activity, are without relevance for the allergic status. In contrast, SOCS1 might be involved in the development of a Th2-skewed immune response and subsequent allergic sensitizations.

Regulatory CD4+ CD25+ T cells prevent thymic dysfunction in experimental chronic colitis

Chronic colitis in T-cell deficient Tg epsilon26 mice develops due to a dysfunction of the thymus which generates colitogenic T cells after bone marrow (BM) transplantation. Regulatory CD4+ CD25+ T cells have been shown to prevent colitis in this model by normalizing the peripheral T-cell pool. We tested the hypothesis that T-cell normalization takes place in the thymus. Tg epsilon26 mice were transplanted with BM (BM-->Tg epsilon26 mice) and consequently received either CD4+ CD25+ or CD4+ CD25- cells from syngenic wild type mice. Furthermore, untransplanted Tg epsilon26 mice received CD4+ CD25+ or CD4+ CD25- cells or complete mesenteric lymph node cells. Transfer of regulatory. CD4+ CD25+ cells normalized the total number of thymocytes and the percentage and number of double positive CD4+ CD8+ cells in transplanted mice while percentage of single positive CD4+ and CD8+ thymocytes in BM-->Tg epsilon26 mice was reduced upon CD4+ CD25+ transfer. Timing of CD4+ CD25+ cell injection was important as transfer later than 7 days after BM transplantation failed to prevent abnormal thymic T-cell distribution in BM-->Tg epsilon26 mice. Isolated CD4+ CD25+ cell transfer without preceding BM transplantation failed to reconstitute thymic architecture. Differences of thymic cell composition could not be exclusively explained by presence or absence of colitis, respectively, because 19 days after BM transplantation when both groups showed no histological signs of colitis, animals transferred with CD4+ CD25+ T cells had a significantly higher percentage and number of CD4+ CD25+ thymocytes and CD4+ Foxp3+ cells than BM-->Tg epsilon26 mice. In conclusion, early CD4+ CD25+ cotransfer prevents thymic dysfunction which underlies immune-mediated bowel inflammation in BM-->Tg epsilon26 mice.

Down-regulation of CD55 and CD46 expression by anti-sense phosphorothioate oligonucleotides (S-ODNs) sensitizes tumour cells to complement attack

Overexpression of one or more membrane-bound complement regulatory proteins (mCRPs) protects tumour cells against complement-mediated clearance by the autologous humoral immune response and is also considered as a barrier for successful immunotherapy with monoclonal anti-tumour antibodies. Neutralization of mCRPs by blocking antibodies, enzymatic removal or cytokine-mediated down-regulation has been shown to sensitize tumour cells to complement attack. In our study we applied, for the first time, anti-sense phosphorothioate oligonucleotides (S-ODNs) to knock down the expression of the mCRPs CD55 and CD46 with the aim of exploiting complement more effectively for tumour cell damage. Potent anti-sense oligonucleotides against CD55 and CD46 were identified by screening various target sequences (n = 10) for each regulator. S-ODN anti-CD55(687) reduced CD55 protein expression up to 84% and CD46 protein expression was inhibited up to 76% by S-ODN anti-CD46(85). Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed a similar reduction of the CD55 and CD46 mRNA levels, which argues for an RNAse H-dependent anti-sense mechanism. T47D, A549 and PC3 cells, representing breast, lung and prostate carcinoma, were used for functional studies. Dependent on the particular cell line, anti-sense-based inhibition of mCRP expression enhanced complement-dependent cytolysis (CDC) up to 42% for CD55 and up to 40% for CD46, and the combined inhibition of both regulators yielded further additive effects in T47D cells. C3 opsonization of CD55/CD46-deficient tumour cells was also clearly enhanced upon mCRP suppression. Due to the clinical applicability of S-ODNs, the anti-sense approach described in this study may offer an additional alternative to improve the efficacy of antibody- and complement-based cancer immunotherapy.

Regulation and functional role of the Runt-related transcription factor-2 in pancreatic cancer

Recent evidence suggests that Runt-related transcription factors play a role in different human tumours. In the present study, the localisation of the Runt-related transcription factor-2 (Runx2), its transcriptional activity, as well as its regulation of expression was analysed in human pancreatic ductal adenocarcinoma (PDAC). Quantitative real-time PCR and immunohistochemistry were used for Runx2 expression and localisation analysis. Runt-related transcription factor-2 expression was silenced using specific siRNA oligonucleotides in pancreatic cancer cells (Panc-1) and immortalised pancreatic stellate cells (IPSCs). Overexpression of Runx2 was achieved using a full-length expression vector. TGF-β1, BMP2, and other cytokines were assessed for their potential to regulate Runx2 expression. There was a 6.1-fold increase in median Runx2 mRNA levels in PDAC tissues compared to normal pancreatic tissues (P<0.0001). Runt-related transcription factor-2 was localised in pancreatic cancer cells, tubular complexes, and PanIN lesions of PDAC tissues as well as in tumour-associated fibroblasts/stellate cells. Coculture of IPSCs and Panc-1 cells, as well as treatment with TGF-β1 and BMP2, led to increased Runx2 expression in Panc-1 cells. Runt-related transcription factor-2 overexpression was associated with decreased MMP1 release as well as decreased growth and invasion of Panc-1 cells. These effects were reversed by Runx2 silencing. In conclusion, Runx2 is overexpressed in PDAC, where it is regulated by certain cytokines such as TGF-β1 and BMP2 in an auto- and paracrine manner. In addition, Runx2 has the potential to regulate the transcription of extracellular matrix modulators such as SPARC and MMP1, thereby influencing the tumour microenvironment.

Interleukin-18 is increased only in a minority of patients with active Crohn's disease

BACKGROUND AND AIMS

It has been suggested that Crohn's Disease (CD) is associated with an elevated T helper 1 response as manifested by increased production of interleukin-18 (IL-18). Local concentrations of neutralizing IL-18 binding proteins (IL-18 bp) may counteract biological functions of mature IL-18 in mucosal inflammation. Therefore, we investigated the IL-18/IL-18 bp system in a large group of patients with active inflammatory bowel disease (IBD) to identify patients that could respond theoretically to IL-18 neutralizing treatment strategies.

PATIENT/METHODS

IL-18 and IL-18 bp messenger RNA (mRNA) expression in colonic mucosa from patients with active CD (n = 72), active ulcerative colitis (UC; n = 32), and non-IBD controls (infectious colitis or diverticulitis; n = 19) and normal, non-diseased controls (n = 20) were measured by reverse-transcribed real-time polymerase chain reaction. Mature IL-18 protein and IL-18 bp expression in inflamed mucosa were assessed by Western blotting.

RESULTS/FINDINGS

Although IL-18 mRNA was increased in some patients with CD, the increase was not statistically significant. Densitometric evaluation of IL-18/alpha-actin ratio in patients with active CD (n = 20) and patients with UC (n = 10) demonstrated an increased ratio of IL-18 protein in CD when compared to UC (1.04 vs 0.72 [median]). On closer inspections, only 7/20 CD patients had an increased IL-18 protein expression in inflamed areas compared to noninflamed mucosa.

INTERPRETATION/CONCLUSION

IL-18 expression in active CD is heterogeneous, only a minority of patients expresses elevated levels. Further treatment strategies targeting IL-18 expression in active CD should be concentrated on this subgroup of patients.

Association of neuropeptides with Th1/Th2 balance and allergic sensitization in children

BACKGROUND

Among neurogenic factors, the neuropeptides have an important regulatory influence on immune system activity and may lead to allergic sensitization.

OBJECTIVE

The aim of our study was to investigate the relationship of the neuropeptides vasoactive intestinal peptide (VIP), somatostatin (SOM) and substance P (SP) on modulation of Th1/Th2 balance and allergic sensitization in children.

METHODS

Within the LISAplus (Life style-Immune system-Allergy) study, blood samples of 321 six-year-old children were analysed for concentration of neuropeptides, Th1 and Th2 cytokines, transcription factors for T cell regulation and suppressors of cytokine signalling. In addition, samples were screened for specific IgE against inhalant and food allergens.

RESULTS

Children with high SOM values showed a Th2 polarization and a reduced expression of FOXP3, the marker for regulatory T cells. High (VIP) levels correlated inversely with the expression of T cell transcription factors (Tbet and SOCS3). In contrast, elevated levels of SP were associated with reduced GATA3 and SOCS3 expression and with increased IFN-gamma concentrations. Allergic sensitization was more prevalent in children with higher SOM and VIP concentrations but not associated with SP levels.

CONCLUSION

Our data reveal an association between neuropeptides and modulatory effects on immune cells in vivo, especially on Th1/Th2 balance with a correlation to allergic sensitization in children. We suggest that elevated SOM and VIP concentrations and the inducing factors should be considered as allergy risk factors.

Increased cytokine transcripts in pouchitis reflect the degree of inflammation but not the underlying entity

BACKGROUND AND AIMS

After ileopouch anal anastomosis (IPAA), 10-40% of patients with ulcerative colitis (UC) but only 5% of patients with familial adenomatous polyposis (FAP) develop pouchitis. Immunoregulatory abnormalities might be of importance in the pathogenesis of the disease. Therefore, we characterized cytokine and chemokine transcripts in inflamed and non-inflamed pouches in patients with UC compared to those with FAP and Crohn's disease (CD).

PATIENTS AND METHODS

Mucosal biopsies were taken from 87 patients with IPAA [UC (n=70), CD (n=8) or FAP (n=9)]. Patients with active ileal CD (n=14), active UC (n=17) and non-inflammatory conditions (n=12) served as controls. The expression of 20 gene transcripts was quantified using real-time polymerase chain reaction.

RESULTS AND FINDINGS

Pro-inflammatory cytokines and chemokines are significantly increased in IPAA patients with acute pouchitis. This increase is independent of the underlying disease (UC or CD) and reflects the degree of inflammation. A good correlation between pouchitis activity (using the Pouchitis Disease Activity Index) and the MRP-14, interleukin-8, macrophage inflammatory protein-2alpha and matrix metalloproteinase-1 transcripts was observed.

INTERPRETATIONS AND CONCLUSIONS

Our data support the view that pouchitis reflects an inflammatory process that is different from that of underlying inflammatory bowel diseases, as the cytokine and chemokine patterns in pouchitis are neither typical of CD nor of UC, but maybe due to bacterial intestinal microflora overgrowth in the pouch lumen. Quantification of transcript levels allows an estimation of the extent of mucosal inflammation and may become helpful in the evaluation of the disease, especially in clinical trials.

The ECM proteoglycan decorin links desmoplasia and inflammation in chronic pancreatitis

BACKGROUND

Recurrent inflammation in chronic pancreatitis (CP) is not well understood.

AIMS

To investigate whether decorin, an extracellular matrix (ECM) proteoglycan with macrophage modulating activity, is a pathogenic factor allowing diseased pancreatic stroma to sustain inflammation by affecting the cytokine profile of accumulating inflammatory cells.

METHODS

Decorin was examined in 18 donors and 32 patients with CP by quantitative reverse transcription polymerase chain reaction (QRT-PCR), western blotting, and immunohistochemistry of pancreatic specimens. QRT-PCR was used to assess cytokine expression in donor peripheral blood mononuclear cells (PBMC), exposed or not to decorin in vitro, and to compare it with the cytokine profile of circulating and resident mononuclear cells (MNC) of patients with CP.

RESULTS

In CP, desmoplasia is associated with overexpression of decorin in the growing ECM and enlarged pancreatic nerves. In culture, exposure of MNC to decorin stimulated expression of the MNC recruiting chemokine MCP-1. In biopsies, MNC infiltrates in decorin rich CP tissue showed a 300-fold upregulation of MCP-1 compared with decorin free peripheral blood, whereas no difference was found in basal MCP-1 expression in PBMC of patients versus donors. This effect was specific for MCP1-other inflammatory cytokines, such as interleukin 1beta and tumour necrosis factor alpha, were not affected.

CONCLUSION

Decorin is a molecular marker of desmoplasia in CP, and excessive decorin may allow fibrotic masses to nourish and protract inflammation by deregulating the process of MNC accumulation and activation. These data provide a molecular basis for surgical resection of diseased tissue as a treatment option in CP.

Development of ulcerative colitis after heart transplantation during immunosuppressive therapy

BACKGROUND

Cardiac transplantation has become an accepted treatment modality for end-stage heart failure. Immunosuppressive agents, which are used after transplantation, are considered as therapeutic options for inflammatory bowel disease.

CASE REPORT

We report on a 53-year-old patient who was treated for 2 years with cyclosporine A, azathioprine and prednisolone after heart transplantation. He developed a distal colitis with all features of ulcerative colitis. An infectious or ischemic etiology was carefully excluded. In spite of high-dose treatment with prednisolone the patient's abdominal symptoms worsened and he developed a progression of the inflammation in the entire colon and a colectomy with ileostomy was necessary. The histology was consistent with ulcerative colitis. After colectomy he recovered and remained in a good state of health.

CONCLUSIONS

This report supports the concept that new onset inflammatory bowel disease can develop in a heart transplantation recipient in spite of immunosuppression.

Liver-specific expression of interferon gamma following adenoviral gene transfer controls hepatitis B virus replication in mice

Interferons control viral replication and the growth of some malignant tumors. Since systemic application may cause severe adverse effects, tissue-specific expression is an attractive alternative. Liver-directed interferon gene therapy offers promising applications such as chronic viral hepatitis B or C or hepatocellular carcinoma and thus needs testing in vivo in suitable animal models. We therefore used the Tet-On system to regulate gene expression in adenoviral vectors, and studied the effect of liver-specific and regulated interferon gamma expression in a mouse model of chronic hepatitis B virus (HBV) infection. In a first generation adenoviral vector, genes encoding for firefly luciferase and interferons alpha, beta or gamma, respectively, were coexpressed under control of the bidirectional tetracycline-regulated promoter P(tet)bi. Liver-specific promoters driving expression of the reverse tetracycline controlled transactivator ensured local expression in the livers of HBV transgenic mice. Following gene transfer, we demonstrated low background, tight regulation and a 1000-fold induction of gene expression by doxycycline. Both genes within the bidirectional transcription unit were expressed simultaneously, and in a liver-specific fashion in cell culture and in living mice. Doxycycline-dependent interferon gamma expression effectively controlled HBV replication in mice, but did not eliminate HBV transcripts. This system will help to study the effects of local cytokine expression in mouse disease models in detail.

Osteopontin influences the invasiveness of pancreatic cancer cells and is increased in neoplastic and inflammatory conditions

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with an overall 5-year survival rate of less than 5%. Invasive tumor growth and early metastasis are two important reasons for this dismal prognosis. Osteopontin (OPN) is a secretory protein with a variety of functions, for example in cell adhesion and migration, inflammatory reaction and apoptosis. In this study the functional role of OPN in human pancreatic cancer and its potential use as a disease marker were analyzed. By real time quantitative PCR, there was a 2.2-fold and 1.6-fold increase of OPN mRNA in pancreatic cancers (n = 23) and chronic pancreatitis samples (n = 22), respectively, compared to normal pancreatic tissues (n = 20). Immunohistochemical analysis demonstrated OPN staining in 60% of the primary pancreatic tumors and in 72% of the lymph node and liver metastases. ELISA analysis of serum samples obtained from pancreatic cancer patients (n = 70), chronic pancreatitis patients (n = 12), and healthy donors (n = 20) showed a 1.6-fold increase in OPN serum levels in patients with tumors and a 1.9-fold increase in patients with chronic pancreatitis. Recombinant human OPN significantly increased the invasiveness of pancreatic cancer cells, without having any impact on cell proliferation. In addition, down regulation of OPN by specific siRNA molecules decreased pancreatic cancer cell invasion. In conclusion, OPN serum levels in pancreatic cancer and chronic pancreatitis patients are not significantly different, thereby restricting its role as a prognostic or follow-up marker. Our results do suggest, however, that blockade of OPN might be useful as a therapeutic approach to inhibit invasion and metastasis of pancreatic cancer cells.

High prevalence of Mycobacterium avium subspecies paratuberculosis IS900 DNA in gut tissues from individuals with Crohn's disease

BACKGROUND AND AIMS

Conflicting results exist about the presence of Mycobacterium avium subspecies paratuberculosis (MAP) specific IS900 DNA in Crohn's disease (CD) tissues. Therefore, we examined IS900 in a large number of gut samples from patients with CD (n = 100) and ulcerative colitis (UC, n = 100), and in non-inflamed control tissues (nIBD, n = 100). We hypothesised that IS900 DNA detection might be associated with distinct clinical phenotypic characteristics in CD.

METHODS

The prevalence of MAP DNA in surgically resected tissues was examined using a mechanical-enzymatic disruption technique and nested IS900 specific polymerase chain reaction (PCR). CD patients were stratified according to the criteria of the Vienna classification and other clinical characteristics.

RESULTS

IS900 PCR detection rate was significantly higher in CD tissue samples (52%) than in UC (2%) or nIBD (5%) specimens (p<0.0001). In CD patients, IS900 DNA was detected in samples from both diseased small bowel (47%) as well as from the colon (61%). No firm association between MAP specific IS900 detection rates and clinical phenotypic characteristics in CD could be established. However, corticosteroid medication constituted a factor which tended to have a negative influence on IS900 DNA detection rates in CD (p<0.01).

CONCLUSIONS

The presence of MAP specific IS900 DNA is a predominant feature of CD. Therapeutic intervention against MAP might represent a potential target for disease mitigation in Crohn's disease.

Expression analysis of MAC30 in human pancreatic cancer and tumors of the gastrointestinal tract

Meningioma-associated protein, MAC30, is a protein with unknown function and cellular localization that is differentially expressed in certain malignancies. In the present study, the expression of MAC30 in a variety of normal and cancerous human gastrointestinal tissues, with special emphasis on pancreatic tissues was analyzed. Quantitative RT-PCR was utilized to compare MAC30 expression levels. In situ hybridization and immunohistochemistry were carried out to localize MAC30 mRNA and protein expression in normal and cancerous tissue samples of the esophagus, stomach, colon and pancreas. Furthermore, the effects of TGF-beta on the transcription of MAC30 mRNA were examined in pancreatic cancer cells. MAC30 mRNA was expressed in a wide variety of normal human tissues, being most abundant in testicular and gastric tissue samples. MAC30 mRNA levels were significantly increased in breast and colon cancer, but significantly decreased in pancreatic and renal cancer. TGF-beta down-regulated MAC30 mRNA levels in certain pancreatic cancer cells. MAC30 protein was localized in normal pancreatic tissues, mainly in acinar and islet cells, and in normal colon, gastric and esophageal tissues especially in the mucosal cells. MAC30 was strongly present in tubular complexes in pancreatic cancer tissues but weak to absent in pancreatic cancer cells of primary tumors and metastases. In contrast, esophageal, gastric and colon tumors displayed strong MAC30 immunoreactivity in the cancer cells. In conclusion, MAC30 is expressed in various normal and diseased human tissues. MAC30 up-regulation in certain tumors and down-regulation in others suggests that this protein plays a distinct role in human malignancies.

Regulatory CD4+CD25+ cells reverse imbalances in the T cell pool of bone marrow transplanted TGepsilon26 mice leading to the prevention of colitis

BACKGROUND AND AIMS

Erroneous thymic selection of developing T lymphocytes may be responsible for the expansion of self reactive T cells or may contribute to the absence of regulatory T cells important in controlling peripheral inflammatory processes. Colitis in bone marrow (BM) transplanted Tgepsilon26 mice is induced by abnormally activated T cells developing in an aberrant thymic microenvironment. We investigated the protective role of regulatory CD4+CD25+ T cells in this model.

METHODS

BM from (C57BL/6 x CBA/J) F1 mice was transplanted into specific pathogen free Tgepsilon26 mice (BM-->Tgepsilon26). Transplanted mice received no cells (control), sorted CD4+CD25+, or CD4+CD25- cells from mesenteric lymph nodes (MLN) of normal mice. MLN cell subsets were analysed using membrane markers. Cytokine secretion of MLN cells was measured using intracellular cytokine staining and cytokine secretion in anti-CD3 stimulated cell cultures. Colitis was measured by histological scores.

RESULTS

CD4+CD25+ cells were reduced in the MLNs of BM-->Tgepsilon26 mice. Transfer of regulatory CD4CD4+CD25+ but not of CD4+CD25- cells reduced the number of MLN CD4+ T cells in BM-->Tgepsilon26 recipients and increased the number of MLN CD8+ cells, thereby normalising the CD4+/CD8+ ratio. CD4+CD25+ but not CD4+CD25- cell transfer into BM-->Tgepsilon26 mice reduced the number of tumour necrosis factor alpha+ CD4+ cells and increased the secretion of transforming growth factor beta by MLN cells. Transfer of 3 x 10(5) CD4+CD25+ cells after BM transplantation into Tgepsilon26 mice prevented colitis whereas CD4+CD25- cells had no protective effect.

CONCLUSIONS

These results suggest that defective selection or induction of regulatory T cells in the abnormal thymus is responsible for the development of colitis in BM-->Tgepsilon26 mice. Transfer of CD4+CD25+ cells can control intestinal inflammation in BM-->Tgepsilon26 mice by normalising the number and function of the MLN T cell pool.

Detection of cardiac allograft rejection by real-time PCR analysis of circulating mononuclear cells

BACKGROUND

Detection of cardiac allograft rejection is based on the histological examination of endomyocardial biopsies (EMB). We have explored the possibility of whether graft rejection could be detected by characteristic gene expression patterns in peripheral blood mononuclear cells (PBMC) of heart-transplant recipients.

METHODS

The study included 58 blood samples of 44 patients. On the day of EMB, mononuclear cells were isolated from peripheral blood, and gene expression was measured by quantitative real-time PCR. Thirty-nine parameters, including cytokine and chemokine genes were analyzed. Gene expression results were correlated with histological assessment of concomitant evaluated EMB according to International Society for Heart and Lung Transplantation (ISHLT) nomenclature.

RESULTS

Gene expression of perforin, CD95 ligand, granzyme B, RANTES, CXCR3, COX2, ENA 78 and TGF-beta1 was significantly different in PBMC of patients with mild to moderate degrees of allograft rejection (> or =grade 2) compared with patients exhibiting no or minor forms of rejection (<grade 2). Using discriminance analysis, five parameters were found that allow discrimination of rejection > or =grade 2 vs. <grade 2 with a sensitivity of 84% and a specificity of 82% as assessed by receiver operating characteristic analysis.

CONCLUSION

Quantitative analysis of gene expression in PBMC may be a valuable tool for non-invasive diagnosis of allograft rejection and may allow further insight in the biological process of graft rejection.

RUNX3 expression in primary and metastatic pancreatic cancer

AIM

Runx transcription factors are important regulators of lineage specific gene expression, cell proliferation, and differentiation. Runx3 expression is lost in a high proportion of gastric cancers, suggesting a tumour suppressive role in this malignancy. This study investigates the expression and localisation of Runx3 in pancreatic tissues.

METHODS

Quantitative polymerase chain reaction was used to measure Runx3 mRNA. Immunohistochemistry was carried out to localise Runx3 in normal pancreatic tissues, and in primary and metastatic pancreatic ductal adenocarcinoma (PDAC). Basal and transforming growth factor beta1 (TGFbeta1) induced Runx3 expression was analysed in cultured pancreatic cancer cell lines.

RESULTS

Runx3 expression was low to absent in normal pancreatic tissues, but increased in a third of cancer tissues. Runx3 was present only in islets in normal pancreas, whereas in pancreatic cancers, Runx3 was detected in the cancer cells of seven of 24 samples analysed. In addition, it was expressed by lymphocytes in six of the 16 cases with lymphocyte infiltration. In pancreatic cancer cell lines, Runx3 mRNA was present in Colo-357 and T3M4 cells, but was low to absent in the other cell lines tested. TGFbeta1 repressed Runx3 mRNA expressed in Colo-357 cells, and had no effect on Runx3 expression in the other pancreatic cancer cell lines.

CONCLUSION

Runx3 expression is restricted to islets in the normal pancreas. In contrast, a considerable proportion of pancreatic tumours express Runx3, and its expression is localised in the tumour cells and in the infiltrating lymphocytes. Thus, Runx3 might play a role in the pathogenesis of PDAC.

Toll-like receptor expression reveals CpG DNA as a unique microbial stimulus for plasmacytoid dendritic cells which synergizes with CD40 ligand to induce high amounts of IL-12

Human plasmacytoid dendritic cells (DC) (PDC, CD123+) and myeloid DC (MDC, CD11c+) may be able to discriminate between distinct classes of microbial molecules based on a different pattern of Toll-like receptor (TLR) expression. TLR1-TLR9 were examined in purified PDC and MDC. TLR9, which is critically involved in the recognition of CpG motifs in mice, was present in PDC but not in MDC. TLR4, which is required for the response to LPS, was selectively expressed on MDC. Consistent with TLR expression, PDC were susceptible to stimulation by CpG oligodeoxynucleotide (ODN) but not by LPS, while MDC responded to LPS but not to CpG ODN. In PDC, CpG ODN supported survival, activation (CD80, CD86, CD40, MHC class II), chemokine production (IL-8, IP-10) and maturation (CD83). CD40 ligand (CD40L) and CpG ODN synergized to activate PDC and to stimulate the production of IFN-alpha and IL-12 including bioactive IL-12 p70. Previous incubation of PDC with IL-3 decreased the amount of CpG-induced IFN-alpha and shifted the cytokine response in favor of IL-12. CpG ODN-activated PDC showed an increased ability to stimulate proliferation of naive allogeneic CD4 T cells, butTh1 polarization of developing T cells required simultaneous activation of PDC by CD40 ligation and CpG ODN. CpG ODN-stimulated PDC expressed CCR7, which mediates homing to lymph nodes. In conclusion, our studies reveal that IL-12 p70 production by PDC is under strict control of two signals, an adequate exogenous microbial stimulus such as CpG ODN, and CD40L provided endogenously by activated T cells. Thus, CpG ODN acts as an enhancer of T cell help, while T cell-controlled restriction to foreign antigens is maintained.

Activation of beta(1) integrins mediates proliferation and inhibits apoptosis of intestinal CD4-positive lymphocytes

A characteristic of lamina propria lymphocytes (LPL) is their low proliferative response to stimuli of the CD3 pathway. beta(1) integrins were expressed on LPL; however, their function is unknown. Therefore, we determined whether beta(1) integrins contribute to T cell responses by providing costimulatory signals. Integrins on CD4(+) LPL of controls and patients with inflammatory bowel disease were characterized by flow cytometry. Cells were stimulated by anti-CD3 or anti-CD2 antibodies either alone or in combination with a stimulatory beta(1) integrin antibody (12G10). Proliferation and apoptosis were measured by [(3)H]thymidine pulsing or flow cytometry. Cytokine mRNA and apoptosis-related transcripts were quantified by reverse transcriptase-PCR. We demonstrated that beta(1) integrin costimulation restored CD3-induced proliferation of CD4(+) LPL and reduced activation-induced apoptosis. Activation of beta(1) integrins by addition of 12G10 antibody to CD3-stimulated cells restored their capacity to express proinflammatory cytokine transcripts. Further, expression of the activated form of beta(1) integrins was significantly elevated on LPL from inflamed mucosa. These studies demonstrate that beta(1) integrin costimulation modulates the response of LPL after TCR stimulation. An increased expression of activated beta(1) integrins on LPL in intestinal inflammation may abolish their unresponsiveness to antigens and perpetuate the inflammatory process.

Separation of stereoisomers in a simulated moving bed-supercritical fluid chromatography plant

The combination of two techniques, simulated moving bed (SMB) and supercritical fluid chromatography (SFC), leads to an apparatus with unique features. Besides the known advantages of the SMB process, like reduced solvent consumption and its continuity, the use of supercritical carbon dioxide as the mobile phase offers an easy product recovery by depressurizing the supercritical fluid. Details of a SMB-SFC plant are presented for the first time. Due to the large number of process parameters a simulation of the SMB process is necessary to achieve optimal operating conditions. The most important thermodynamic information for a SMB process is the adsorption isotherms. Therefore, isotherms for two phytol isomers are measured and correlated. A fast dynamic model for the simulation of SMB is used to calculate the region of complete separation taking different column configurations and the compressibility of the mobile phase into account.

Biochemical and functional analysis of mice deficient in expression of the CD45-associated phosphoprotein LPAP

The role of the CD45-associated phosphoprotein (LPAP / CD45-AP) during an immune response remains unclear. To understand better the function of LPAP we generated LPAP-deficient mice by disrupting exon 2 of the LPAP gene. LPAP-null mice were healthy and did not show gross abnormalities compared to their wild-type littermates. However, immunofluorescence analysis of T and B lymphocytes revealed a reduced expression of CD45, which did not affect a particular subpopulation. In contrast to a recent report (Matsuda et al., J. Exp. Med. 1998. 187: 1863 - 1870) we neither observed significant alterations of the assembly of the CD45 / lck-complex nor of polyclonal T-cell responses. However, lymphnodes from LPAP-null mice showed increased cellularity, which could indicate that expression of LPAP might be required to prevent expansion of lymphocytes in particular lymphatic organs rather than potentiating immune responses.

Protection of trinitrobenzene sulfonic acid-induced colitis by an interleukin 2-IgG2b fusion protein in mice

BACKGROUND & AIMS

We have shown in previous studies that an interleukin 2 (IL-2)-IgG2b fusion protein suppresses both humoral and cellular immune reactions in a murine model of DTH reaction. We now analyze the effects of IL-2-IgG2b in a model of intestinal inflammation in mice induced by the hapten reagent 2,4, 6-trinitrobenzene sulfonic acid (TNBS) that mimics immunologic characteristics of human Crohn's disease.

METHODS

In TNBS-induced colitis, colonic and splenic T-cell subsets were characterized by immunohistochemistry and flow cytometry. Cytokine synthesis was studied by semiquantitative reverse-transcription polymerase chain reaction and intracellular cytokine staining in CD4(+) T cells.

RESULTS

When mice were treated with IL-2-IgG2b, improvement in both wasting disease and histopathologic signs of colonic inflammation was observed. An increase in the number of colonic CD4(+)/CD25(+) T cells and increased synthesis of the immunosuppressive cytokine IL-10 also occurred. The protective role of IL-10 was demonstrated by the finding that neutralization of IL-10 in vivo using IL-10-specific antibodies inhibited the IL-2-IgG2b effects in TNBS-induced colitis.

CONCLUSIONS

These studies show for the first time that the IL-2-IgG2b fusion protein can abrogate experimental colitis by local induction of IL-10-secreting T cells.

Generation of switch hybrid DNA between Ig heavy chain-mu and downstream switch regions in B lymphocytes

Ig heavy chain isotype switching in B lymphocytes is known to be preceded by transcription of a portion of the particular heavy chain gene segment that is targeted for recombination. Here, we describe an active role for these transcripts in the switch recombination process. Using an in vitro assay that exposes an artificial switch-mu (Smu) minisubstrate to switch region transcripts in the presence of nuclear extracts from switching cells, we demonstrate that free 3' ends of the Smu sequence are extended onto switch region transcripts by reverse transcription. The activity was induced in splenic B lymphocytes upon activation with LPS or CD40 ligand. This in vitro process is thought to be relevant to in vivo class switching for two reasons: 1) although only one-third of the Smu minisubstrate actually contains Smu sequence, all crossovers between switch regions occurred in the Smu portion; and 2) treatment of B lymphocytes with IL-4, which enriches for switching to S gamma 1, increases the ratio of Smu-S gamma 1 to Smu-S gamma 3 hybrids by 16% after LPS treatment and by 37% after CD40 ligand activation, implicating this S mu-primed reverse transcription of switch region transcripts as a novel mechanism of regulating the specificity of isotype switching. Further evidence for an active role of switch region transcripts was obtained by expressing S alpha RNA in trans in the Bcl1B1 B lymphoma line. Endogenous S mu-S alpha switch circles were detected in Bcl1B1 cells expressing exogenous S alpha RNA but not in mock-transfected cells.

Spontaneous development of plasmacytoid tumors in mice with defective Fas-Fas ligand interactions

B cell malignancies arise with increased frequency in aging individuals and in patients with genetic or acquired immunodeficiency (e.g., AIDS) or autoimmune diseases. The mechanisms of lymphomagenesis in these individuals are poorly understood. In this report we investigated the possibility that mutations at the Fas (lpr) and Fasl (gld) loci, which prevent Fas-mediated apoptosis and cause an early onset benign lymphoid hyperplasia and autoimmunity, also predispose mice to malignant lymphomas later in life. Up to 6 mo of age, hyperplasia in lpr and gld mice results from the predominant accumulation of polyclonal T cell subsets and smaller numbers of polyclonal B cells and plasma cells. Here, we examined C3H-lpr, C3H-gld, and BALB-gld mice 6-15 mo of age for the emergence of clonal T and B cell populations and found that a significant proportion of aging mice exclusively developed B cell malignancies with many of the hallmarks of immunodeficiency-associated B lymphomas. By 1 yr of age, approximately 60% of BALB-gld and 30% of C3H-gld mice had monoclonal B cell populations that grew and metastasized in scid recipients but in most cases were rejected by immunocompetent mice. The tumors developed in a milieu greatly enriched for plasma cells, CD23- B cells and immunodeficient memory T cells and variably depleted of B220+ DN T cells. Growth factor-independent cell lines were established from five of the tumors. The majority of the tumors were CD23- and IgH isotype switched and a high proportion was CD5+ and dull Mac-1+. Considering their Ig secretion and morphology in vivo, most tumors were classified as malignant plasmacytoid lymphomas. The delayed development of the gld tumors indicated that genetic defects in addition to the Fas/Fasl mutations were necessary for malignant transformation. Interestingly, none of the tumors showed changes in the genomic organization of c-Myc but many had one or more somatically-acquired MuLV proviral integrations that were transmitted in scid passages and cell lines. Therefore, insertional mutagenesis may be a mechanism for transformation in gld B cells. Our panel of in vivo passaged and in vitro adapted gld lymphomas will be a valuable tool for the future identification of genetic abnormalities associated with B cell transformation in aging and autoimmune mice.

A cytokine cascade including prostaglandin E2, IL-4, and IL-10 is responsible for UV-induced systemic immune suppression

Even though all of the energy contained with the UV wavelengths of solar radiation is absorbed within the epidermis and upper layers of the dermis, UV irradiation can suppress immune responses to Ag introduced at distant nonirradiated sites. In addition, data from a number of laboratories have suggested that one consequence of UV exposure is suppressed Th1 cell activation with normal or enhanced Th2 cell activation, resulting in a shift to a Th2-like phenotype. Cytokines secreted by UV-irradiated keratinoctyes, particularly IL-10, have been shown to play a major role in the induction of systemic immune suppression and differential activation of T helper cell subsets. Although IL-10 can influence Th1 cell activation by altering Ag presentation and suppressing IFN-gamma secretion, the major signal for the development of a Th2 response is IL-4. Here we tested the hypothesis that UV irradiation induces IL-4 secretion. UV irradiation induced serum IL-4 in a dose-dependent fashion. Injecting UV-irradiated mice with anti-IL-4 blocked immune suppression. We could find no evidence, however, supporting secretion of IL-4 by UV-irradiated keratinocytes. Rather, we suggest that prostaglandins released by irradiated keratinocytes induce serum IL-4 since treating UV-irradiated mice with a cyclooxygenase-2 inhibitor blocked its production. Moreover, we found that treating UV-irradiated mice with anti-IL-4 suppressed serum IL-10 levels. In addition, injecting normal mice with PGE2 induced serum IL-4 and IL-10. We suggest that UV exposure activates a cytokine cascade (PGE2 --> IL-4 --> IL-10) that ultimately results in systemic immune suppression.

The catalytic domain of protein kinase C-delta in reciprocal delta and epsilon chimeras mediates phorbol ester-induced macrophage differentiation of mouse promyelocytes

The overexpression of protein kinase C-delta (PKC-delta), but not PKC-epsilon, enables the mouse myeloid cell line 32D to differentiate into macrophages when treated with phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA). To determine the domain of PKC-delta that is responsible for this isotype-specific function, cDNAs that encode reciprocal chimeras of PKC-delta and -epsilon (PKC-delta epsilon and PKC-epsilon delta) were constructed by exchanging regulatory and kinase domains using polymerase chain reaction technology. Both chimeras were stably expressed in 32D cells using the pLTR expression vector and displayed protein kinase activity upon TPA treatment. TPA treatment of L epsilon delta, cells that overexpressed the PKC-epsilon delta chimera, induced a dramatically increased cell volume, surface adherence, surface expression of Mac-1 and Mac-3, lysozyme production, and phagocytosis. These are the characteristics of the macrophage phenotype found in TPA-treated 32D cells that overexpressed PKC-delta. In contrast, little effect was seen in L delta epsilon, 32D cells that overexpressed PKC-delta epsilon, with or without TPA treatment. A PKC inhibitor directed toward the catalytic domain of PKC, GF109203X, and a selective inhibitor of PKC-delta, Rottlerin, blocked the TPA-induced differentiation of PKC-epsilon delta-overexpressing 32D cells. These results demonstrate that the catalytic domain of PKC-delta contains the primary determinants for its activity in phorbol ester-induced macrophage differentiation.