Susceptibility to ovarian endometriosis in Polish population is not associated with HLA-DRB1 alleles

BACKGROUND

Endometriosis is associated with inflammatory autoimmune reactions; however, aetiopathogenesis of the disease is still poorly understood. While autoimmune disorders are often associated with particular HLA alleles, the possible involvement of HLA in the aetiopathogenesis of endometriosis is still a subject of controversy. The aim of the study was to examine the distribution of HLA-DRB1 alleles in women with endometriosis. To ensure homogeneity of the studied group, only women with ovarian endometrial cysts were included.

METHODS

The study included 65 Polish patients of Caucasian origin in whom ovarian endometriosis had been confirmed by laparoscopic and histopathological examinations. HLA-DRB1 alleles were typed using a reverse slot blot method. A frequency of particular HLA-DRB1 alleles in patients was compared with that of a control group of 700 unrelated ethnically matched individuals as well as 193 age-matched women without endometriosis.

RESULTS

No statistically significant differences were found in the distribution of HLA-DRB1 alleles in patients with ovarian endometriosis as compared with control populations.

CONCLUSIONS

The results of the present study show that ovarian endometriosis is not associated with particular HLA-DRB1 allele(s). This may suggest that aetiology of this form of endometriosis may be not primarily associated with class II HLA-mediated autoimmune reactions.

Circulating soluble tumour necrosis factor receptors in patients with epidermodysplasia verruciformis as compared to patients with cutaneous tumours in the general population

Soluble tumour necrosis factor receptors type I and II (sTNF-RI and II) were evaluated in sera from patients with epidermodysplasia verruciformis and patients with cutaneous warts, actinic keratoses, squamous cell carcinomas or basal cell carcinomas by specific enzyme-linked immunobiological assays. In patients with widespread epidermodysplasia verruciformis lesions, the levels of both sTNF-Rs were in normal range. Both types of sTNF-Rs were significantly increased in patients with warts. The levels of sTNF-RI were significantly increased in patients with multiple actinic keratoses, squamous cell carcinoma and basal cell carcinoma. Increased levels of circulating sTNF-Rs may facilitate development of cutaneous tumours. Normal levels of sTNF-Rs in patients with epidermodysplasia verruciformis might, at least partially, contribute to a slow growth and low metastatic potential of cancers in these patients.

Natural cell-mediated cytotoxicity of peripheral blood lymphocytes against target cells transfected with epidermodysplasia verruciformis-specific human papillomavirus type 8 L1 DNA sequences

The aim of the present study was to characterise natural cell-mediated cytotoxicity against COS-7 cells transfected with potentially oncogenic HPV-8 L1 DNA sequences cloned in sense and antisense orientation and to evaluate their lysis by peripheral blood lymphocytes (PBL) from patients with epidermodysplasia verruciformis (EV), a rare disease associated with life-long infection by specific HPV types. COS-7 cells were transfected with HPV-8 Hinc II restriction fragment (nucleotide positions 5434-7654) cloned in sense (COS-L1S) and antisense (COS-L1A) orientation into pCB6 expression vector. Cytotoxic activity of isolated PBL against COS cell lines as well as K562 erythroleukaemic cells was evaluated by 51Cr-release assay. We found that lymphocytes responsible for natural lysis of COS and K562 cells are CD3-negative CD56-positive natural killer (NK) cells. Analysis of NK cell cytotoxic activity against different COS cell lines has revealed that lymphocytes from healthy subjects killed COS-L1S cells significantly more efficiently than wild COS-7 and COS-L1A cells. Significantly more efficient lysis of COS-L1S cells was also observed in EV patients. Thus, expression of HPV L1 renders target cells more susceptible to NK-mediated cytotoxicity that may enable more effective elimination of transformed cells.

AAF-cmk sensitizes tumor cells to trail-mediated apoptosis

TRAIL is a member of the tumor necrosis factor (TNF) superfamily. This cytokine is cytotoxic for a high proportion of tumor cells, but could be also toxic for normal cells. There is a need to find other agents able to potentiate the antitumor effects of this cytokine. In our study, we found that Ala-Ala-Phe-chloromethylketone (AAF-cmk) augmented cytotoxic activity of TRAIL or TNF against human leukemic cells. Flow cytometry studies and electron microscopy revealed that apoptosis was primarily responsible for this potentiation. Altogether, our studies indicate that AAF-cmk might effectively sensitize human leukemia cells to apoptosis induced by TRAIL and TNF.

Clinical aspects of disrupted Hedgehog signaling (Review)

The Hedgehog (HH) signaling pathway is involved in patterning and development of a variety of organ systems, including the nervous system, the skeletal system, the craniofacial structures, and the gastrointestinal tract. Recent evidence also implicates this signaling pathway in the postembryonic regulation of stem-cell number in epithelia and blood. The family of HH proteins consists of at least three different members, i.e., sonic HH (SHH), Indian HH (IHH), and desert HH (DHH). SHH is the most broadly expressed member of this family and is probably responsible for the major effects of this signaling pathway. The HH signal is received and transduced via a specific receptor complex composed of patched (PTCH) and smoothened (SMOH) transmembrane proteins. Abnormalities in this signaling cascade have been found in various developmental pathologies and neoplasms such as basal cell carcinoma. The abnormalities are associated with congenital or sporadic genetic alteration affecting function of different components of the HH signaling pathway, including SHH, PTCH, SMOH and GLI proteins.

[Experimental closure of bronchial stump after pneumonectomy with the greater omentum]

Authors present their results with experimental closure of bronchial stump after pneumonectomy with pedicled flaps of the greater omentum in sheep. In the experimental group left thoracotomy and laparotomy was performed. The left lung was resected and the bronchial stump was closed with the pedicled flap of the greater omentum. In controls standard left pneumonectomy was performed. After different periods of time (1-12 weeks) the animals were sacrificed, the bronchial stumps were excised and submitted to pathological studies. In none case bronchial fistula occurred. Pathological studies showed that the omentum at the base of the bronchial stump was transformed in the fibrous tissue. The bronchial epithelium begins to cover the omentum in 4 weeks after the operation and this process is finished in 12 weeks after the operation. Pedicled flap of the greater omentum seems to be useful in surgical treatment of bronchial fistulas.

Potential application of cytokine level measurement in corneal epithelium

The aim of the work was to evaluate whether rat corneal epithelial (RtCE) cell line, spontaneously established from rat corneal epithelium in our laboratory, could be used for the evaluation of cornea inflammatory state. Production of proinflammatory cytokines IL-1beta, IL-6 and TNF-alpha by RtCE line in response to a non-specific irritating agent (Triton) was tested. Supernatants from RtCE cells treated for 1 h with 20 microM, 50 microM and 100 microM Triton, were collected after 1 and 24 h, and tested with enzyme-linked immunosorbent assay (ELISA) for IL-1beta, IL-6 and TNF-alpha. The control groups did not produce significant levels of any of the cytokines. However, after stimulation with Triton, the cells did not produce TNF-alpha, while the concentration of IL-1beta and IL-6 increased over 10 times. These results show that in response to a proinflammatory agent RtCE line produces cytokines that could be used for measuring the effect of irritants on the cornea.

Production of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha by a rat corneal epithelial cell line

Production of interleukin (IL)-1 beta, IL-6 and tumor necrosis factor (TNF)-alpha by rat corneal epithelial cells in response to lipopolysaccharide and phorbol-12-myristate-13-acetate (PMA) was tested. Supernatants from rat corneal epithelial cells treated with lipopolysaccharide and PMA were collected after 6, 24 and 48 h and tested with enzyme-linked immunosorbent assay for IL-1 beta, IL-6 and TNF-alpha. The activity of TNF-alpha was additionally confirmed with bioassay on L929 cells. It was found that control groups did not produce significant levels of either cytokine. However, after stimulation with lipopolysaccharide, cells produced mainly IL-6, whereas after PMA they produced mainly TNF-alpha. IL-6 levels 24 and 48 h after PMA stimulation were also elevated, which could have been caused by the presence of TNF-alpha. Production of IL-1 beta in all groups was very low and remained within the test sensitivity range. These results show that the rat corneal epithelial cell line produces inflammatory cytokines in response to proinflammatory mediators. For this reason, it could be used for measuring the effects of irritants on the cornea.

Augmented pro-apoptotic effects of TRAIL and proteasome inhibitor in human promonocytic leukemic U937 cells

TRAIL, Tumor necrosis factor-related apoptosis-inducing ligand), a member of the TNF family, is known to be cytotoxic for a high proportion of tumor cell lines. However, successful application of TRAIL in tumor therapy may depend on finding other agents that can potentiate its antitumor effects. The present study showed that the cytostatic/cytotoxic TRAIL activity against U937 cells could be significantly augmented by proteasome inhibitor PSI, as revealed by MTT assay. Increased cytostatic/cytotoxic effect on U937 cells by TRAIL/PSI combined treatment was caused by apoptosis, as shown by an increased PARP cleavage rate. TRAIL/PSI did not affect the level of mRNA expression for TRAIL receptors (DR4, DR5, DcR1) and other apoptosis signal transduction molecules (TRADD, caspase-8).

Characterisation of epithelial cell line from rat cornea

PURPOSE

Characterisation of RtCE-1 cells, newly established rat corneal epithelial cell line.

METHODS

Morphology of RtCE-1 cells was characterised by light and electron microscopy. Expression of cytokeratins was studied by polyacrylamide electrophoresis and Western blotting. Characterisation of RtCE-1 cells also included karyotype analysis and in vitro study of growth kinetics.

RESULTS

The line shows morphological similarities to normal corneal epithelium. The cells express cornea-specific cytokeratins. Karyotype analysis revealed that the cells are polyploid with modal number of chromosomes at passage 30 equalling 72 +/- 14. Growth of the line is partially dependent on EGF.

CONCLUSION

RtCE-1 cells may constitute a model for the evaluation of proliferation, function and differentiation of corneal epithelium in vitro.

[Studies on conditions for the culture of rabbit corneal epithelium]

PURPOSE

Research was aimed at comparison of isolation methods as well as determination of growth and differentiation dynamics of rabbit corneal epithelium (CE) in vitro. Adhesion, growth and differentiation of CE cells growing on collagen membranes were evaluated.

MATERIAL AND METHODS

Research was performed on the cells of rabbit corneal epithelium isolated mechanically or enzymatically (Dispase II) from comeas excised at the edge of limbus. CE cells were cultured in media with high or low contents of calcium, with addition of FCS, insulin, cholera toxin and EGF.

RESULTS

In comparison with mechanical isolation, enzymatic isolation yielded 4-5 times more living undifferentiated (CE) cells. The highest dynamics of in vitro growth was observed in primary cultures in low-calcium medium supplemented with the above substances. After 20 population doublings cells were differentiated and died. Only few cells on collagen membranes adhered to the collagen but did not enter division.

CONCLUSIONS

Current research allowed for determination of methodology for CE excision and isolation. Optimal conditions for in vitro growth have been established. Growth dynamics and proliferation of CE in vitro have been evaluated. Growth of CE on standard collagen membrane has not been observed.

[Signal transduction mechanisms induced by epidermal growth factor receptor (EGFR) and their role in apoptosis regulation]

Stimulation of epidermal growth factor receptor (EGFR) leads to cell proliferation and plays an important role in cancerogenesis. It seems that these effects are a consequence of triggering of various signal transduction pathways involving PI-3K and MAP kinase activation. Surprisingly, under certain circumstances stimulation of EGFR may also result in cell growth arrest and apoptosis induction. It is possible that anti-proliferative effect of EGF depends on STAT protein activation. It has been reported, that STAT upregulates expression of cyclin-dependent kinase inhibitor, which blocks the cell cycle. Additionally, STAT may increase caspase 1 (ICE) expression, which seems to be necessary for apoptosis induced by EGF. Intracellular mechanisms involved in EGFR proapoptotic activity still remains poorly understood and, because of their potential clinical significance, require further investigation.

[Induction of apoptosis by receptors for factors from the TNF family]

Mechanisms leading to induction of apoptosis by TNF family receptors involve intracellular activation of cysteinyl-aspartate-specific proteases (caspases). Caspase activation requires engagement of adaptor proteins. It is plausible, that caspase activation is sufficient for cell death in course of receptor-dependent induction of apoptosis. However, there are some data that programmed cell death involves also generation of ceramides, arachidonic acid metabolism, or MAP kinase (SAPK/JNK) activation. On the other hand, TNF receptor family triggers some protective, anti-apoptotic mechanisms, i.e. protein kinase C (PKC) and NF-kappa B. The outcome of induction of apoptosis by TNF receptor family depends on the cell type, its physiological condition and influence of environmental factors.

[Morphological characteristics of epithelial cell line from rat cornea]

PURPOSE

Morphological characteristics of established cell line (RtCE) derived from rat anterior corneal epithelium.

MATERIAL AND METHODS

Morphology of cultured RtCE cells was evaluated by light and electron microscopy. Anterior corneal epithelium of rat served as control.

RESULTS

Both in light and electron microscope we observed morphological similarity with anterior corneal epithelium (several layers of cells, numerous desmosomal connections). Moreover, similar morphological changes were observed in relation to the control material, i.e. degeneration and flattening of cells in superficial layers.

CONCLUSIONS

The morphological analysis of RtCE cell line proves its usefulness for further cytomorphological, cytogenetical and functional analyses, as well as for evaluation of influence of different physico-chemical and biological factors on growth and regeneration of corneal epithelium in vitro.

Natural killer cell activity and sex hormone levels in mastopathy

The aim of the study was to test the cytotoxic activity of peripheral blood natural killer (NK) cells in relation to serum levels of sex hormones in patients with mastopathy. The study included 37 patients classified into mastalgia, fibrosis, fibrocystic disease, and fibroadenoma groups and 19 healthy age-matched volunteer women. Estradiol, progesterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin were evaluated in sera by specific radioimmunoassays. NK cell activity was evaluated by means of 51Cr-release assay. In all patient groups, progesterone levels were significantly decreased. There was also an increased frequency of patients with low levels of estradiol (< 50 pg/ml). On the other hand, LH levels in fibrocystic disease and fibroadenoma groups were significantly increased. NK cell activity was in the normal range in all patient groups. In individual women, NK cell cytotoxicity did not correlate with the levels of the studied hormones. However, in patients with low (< 50 pg/ml) and high (> 200 pg/ml) estradiol levels an increase and a decrease of NK cell activity was observed, respectively. This suggests that in patients with mastopathy, estradiol may directly or indirectly affect NK cell cytotoxicity. High levels of estradiol and low NK cell activity might constitute an increased risk for neoplasia.

Serum levels of soluble tumor-necrosis-factor receptors in patients with benign and malignant HPV-associated anogenital lesions

The levels of type-I and type-II soluble TNF-alpha receptors (sTNF-Rs) were evaluated in sera from patients with various human-papillomavirus-(HPV)-associated benign and malignant anogenital lesions using specific enzyme-linked immunobiological assays. In patients with benign HPV6/11-associated condylomata acuminata, the levels of sTNF-RI were significantly increased, while sTNF-RII were in normal range. Both types of sTNF-Rs were in normal range in patients with benign HPV16-associated grade-I/II and grade-III cervical intra-epithelial neoplasia. However, their levels were significantly increased in patients with HPV16/18-associated squamous cervical cancer and anogenital Bowen's carcinoma. Sera from patients with condylomata acuminata and anogenital carcinomas displayed significantly increased TNF-alpha-inhibitory activity, as revealed by L929 cell-cytotoxicity assay. Increased serum TNF-alpha-inhibitory activity correlated with higher levels of sTNF-Rs. Furthermore, this inhibitory activity could be specifically abrogated by htr9 and utr1 monoclonal antibodies recognizing TNF-RI and TNF-RII respectively. Our results strongly suggest that serum sTNF-Rs may protect tumor cells from cytotoxic/cytostatic effects of locally released TNF-alpha, and that elevated levels of circulating sTNF-Rs may facilitate the growth of HPV-associated anogenital lesions.

Immunological response against allogeneic chondrocytes transplanted into joint surface defects in rats

Rat chondrocytes isolated from the articular-epiphyseal cartilage complex were transplanted into defects prepared in articular cartilage and subchondral bone. Transplants were taken for examination after 3 and 8 wk. Cartilage formed by syngeneic chondrocytes did not evoke formation of infiltrations. Contrary to that, in the vicinity of cartilage produced by allogeneic chondrocytes numerous infiltrating cells were present and cartilage resorption could be observed. Cyclosporine-A (CsA) treatment of recipients of allogeneic chondrocytes only partially suppressed accumulation of infiltrating cells and matrix resorption. Antichondrocyte immune response of chondrocyte graft recipients was studied by evaluation of spleen mononuclear cells (SMC) stimulation in mixed splenocyte-chondrocyte cultures and by evaluation of antichondrocyte cytotoxic antibodies. No difference in stimulation of SMC from intact rats by syngeneic and allogeneic chondrocytes was observed. Stimulation by allogeneic chondrocytes was slightly but significantly higher in recipients of syngeneic grafts. SMC of allogenic chondrocyte recipients were strongly stimulated by allogeneic chondrocytes. This response was absent in recipients treated with CsA. Spontaneous antichondrocyte cytotoxic antibody activity was detected in intact rats and in recipients of syngeneic grafts. In recipients of allogeneic chondrocytes the antibody response against allogeneic chondrocytes was raised but was statistically not significant owing to the considerable variation in the level of spontaneously occurring antichondrocyte antibodies.

Apoptosis induced in L1210 leukaemia cells by an inhibitor of the chymotrypsin-like activity of the proteasome

Of a number of factors involved in apoptosis, protease activity may play a crucial role. We show that N-benzyloxycarbonyl-Ile-Glu( O-t-butyl)-Ala-leucinal (PSI), a selective inhibitor of the chymotrypsin-like activity of the proteasome, induces massive apoptosis in murine leukaemia L1210 cells. At 50 nM concentration, PSI induces a block of cytokinesis, while higher concentrations (500 nM) cause S phase block and massive apoptosis. Z-Leu-leucinal, a specific calpain inhibitor, did not induce apoptosis. In contrast to previous reports, TNF-alpha did not enhance apoptosis when combined with PSI. Our results suggest that proteasome inhibitors may be considered as potential anti-neoplastic agents.

Progressive growth of human papillomavirus type 16-transformed keratinocytes is associated with an increased release of soluble tumour necrosis factor (TNF) receptor

Analysis of conditioned media generated by weakly and highly tumorigenic SKv-1 keratinocyte lines harbouring integrated human papillomavirus type 16 (HPV16) DNA sequences revealed a factor inhibiting TNF-alpha and TNF-beta cytotoxic activity. This inhibitory activity was specifically blocked by htr-9 monoclonal antibody (MAb) recognising 55/60 kDa type I TNF receptor suggesting that it is related to a soluble form of this particular receptor (sTNF-RI). The presence of sTNF-RI was confirmed by Western blot analysis of SKv-1 cell-conditioned medium showing a band of 31.5 kDa as well as by the specific enzyme-linked immunobiological assay (ELIBA). Release of sTNF-RI was a result of shedding because Northern blot analysis showed that SKv-1 cells expressed a full-length TNF-RI mRNA, and radioimmunoprecipitation of TNF-RI from [32S]cysteine-labelled cell extracts demonstrated the presence of normal 55 kDa molecule. Evaluation by ELIBA showed that highly tumorigenic SKv-12 cells released significantly more sTNF-RI than their weakly tumorigenic SKv-11 parental cells. Furthermore, human recombinant as well as SKv cell-derived sTNF-RI stimulated proliferation of weakly tumorigenic SKv-11 cells. This suggests that a progressive growth of some neoplastic cells may be, at least partially, a result of an increased spontaneous release of sTNF-RI that enables the cells to escape from local TNF-alpha-mediated growth inhibition.

Rejection of cartilage formed by transplanted allogeneic chondrocytes: evaluation with monoclonal antibodies

Cellular infiltrates participating in rejection of cartilage formed by transplanted allogeneic rat epiphyseal chondrocytes were evaluated immunohistochemically using a panel of different monoclonal antibodies. One week after transplantation, the grafts were surrounded by numerous class II MHC+ (OX6+, OX17+), CD4+ (W3/25+), and W3/13+ cells as well as some ED1+ monocytes/macrophages. Only a few T (OX19+) and B (HIS14+) cells were present. The number of class II MHC+ cells and ED1+ monocytes/macrophages did not change significantly in the course of rejection whereas the number of CD4+ and W3/13+ cells gradually decreased. On the other hand, there was a significant increase in the number of CD8+ (OX8+) cells. CD8+ cells accumulated close to the transplants and some of them penetrated cartilage matrix suggesting that they might be involved in chondrocyte killing. After 3 months, cartilage was almost completely destroyed and the intensity of infiltrations was markedly decreased. Fibrous connective tissue predominated, however, some class II+ as well as few ED1+, CD4+ and CD8+ cells were still present adjacent to the cartilage remnants. At the time of transplantation, chondrocytes were endowed with RT1.D class II antigen (OX17+), but they did not react with OX6 mAb (monoclonal antibody) recognizing the RT1.B class II molecule. However, after 1 week, some chondrocytes reacted with OX6 mAb and the number of RT1.B positive chondrocytes increased in the course of cartilage rejection.

Increased tumorigenicity of human keratinocytes harboring human papillomavirus type 16 is associated with resistance to endogenous tumor necrosis factor-alpha-mediated growth limitation

The aim of this study was to evaluate the relationship between tumorigenicity of cell sublines derived from weakly tumorigenic SKv-e and SKv-l keratinocytes harboring human papillomavirus type 16 (HPV16) and their susceptibility to autocrine growth limitation mediated by tumor necrosis factor-alpha (TNF-alpha). These sublines displayed different in vitro proliferative potential which correlated with tumorigenicity in nu/nu mice. Recombinant TNF-alpha inhibited in vitro growth of weakly tumorigenic parental SKv cell lines while it did not affect proliferation of their respective highly tumorigenic sublines. Resistance to TNF-alpha correlated with both increased in vitro proliferation and tumorigenicity. Anti-TNF-alpha antibodies (Ab) significantly increased in vitro proliferation of weakly tumorigenic parental SKv cells up to the levels of their highly tumorigenic sublines. Growth of highly tumorigenic SKv cells was not affected. On the other hand, proliferation of SKv cells was affected neither by transforming growth factor-beta (TGF-beta) nor by anti-TGF-beta Ab. All SKv cell sublines tested spontaneously released TNF-alpha, as evaluated by a specific radioimmunoassay; however, the levels of the endogenous cytokine were not related to their proliferative potential and tumorigenicity. An increased resistance to the anti-proliferative effect of TNF-alpha may be associated with decreased expression of TNF-alpha receptors (TNF-alpha R) inasmuch as evaluation of 125I-TNF-alpha binding and Northern-blot analysis of TNF-alpha R-specific mRNA showed that highly tumorigenic SKv cell sublines expressed significantly lower numbers of TNF-alpha R than their respective parental cells. These results show that an increased tumorigenicity of HPV16-harboring SKv keratinocytes may be, at least partially, due to escape from autocrine TNF-alpha-mediated growth limitation.

Differences in cartilage formed intramuscularly or in joint surface defects by syngeneic rat chondrocytes isolated from the articular-epiphyseal cartilage complex

Syngeneic rat chondrocytes isolated from the articular-epiphyseal cartilage complex were suspended in hyaluronic acid and transplanted intramuscularly or into joint surface defects. Transplants were fixed in ruthenium hexammonium trichloride and embedded in glycol methacrylate. In cartilage nodules produced intramuscularly, chondrocyte hypertrophy and matrix calcification were observed after 2 wk. Partial ossification occurred after 4 wk and the cartilage was almost completely replaced by an ossicle after 8 wk. Only small, dispersed groups of chondrocytes remained within the ossicle. In cartilage formed in joint surface defects a superficial and a deep zone were distinguished. Chondrocytes in the superficial zone did not hypertrophy and cartilage remained unossified. In the deep zone matrix calcification and bone formation occurred. These processes were, however, retarded in comparison with intramuscular transplants. Thus, either intraarticular environment exerted an inhibitory effect on chondrocyte hypertrophy and matrix calcification or articular chondrocytes present among transplanted cells accumulated close to the joint lumen and reconstructed normal articular cartilage.

NK-cell activity in patients with HPV16-associated anogenital tumors: defective recognition of HPV16-harboring keratinocytes and restricted unresponsiveness to immunostimulatory cytokines

Peripheral blood mononuclear cells (PBMC) from patients with active HPV16-associated pre-malignant and malignant anogenital lesions display a significantly decreased NK-cell activity against HPV16-harboring SKv keratinocytes (NK/SKv) while their cytotoxicity against erythroleukemic K562 cells (NK/K562) remains unaffected. A similar defect can also be seen in some healthy individuals displaying no symptoms of HPV infection (low responders). Analysis with specific Leu IIa monoclonal antibodies (MAbs) has revealed that all patients as well as weakly responding control subjects had normal numbers of circulating CD16+ NK cells. However, PBMC from patients with active disease and weakly responding controls displayed a significantly decreased ability to bind SKv cells. Binding of K562 was in the normal range. In patients in whom the lesions were successfully removed or regressed spontaneously (patients with no lesions), NK/SKv activity did not differ from that of normally responding healthy subjects and the ability of their PBMC to bind SKv cells was unaffected. To determine whether an abrogated NK/SKv cytotoxicity may be corrected by NK-cell stimulatory cytokines. PBMC were pre-incubated overnight with IL-2 and interferon-alpha. Both cytokines stimulated NK/K562 activity in all tested groups. Significant stimulation of NK/SKv activity was observed in PBMC from normal and weakly responding controls as well as patients with no lesions. No increase could be seen in patients with active disease. Evaluations of NK-cell activity before and after surgical removal or spontaneous regression of the lesions showed normalization of primarily depressed NK/SKv activity. Malignant progression was associated with a significant drop in SKv cell killing. Our results suggest that abrogation of NK-cell activity against HPV16-harboring targets in patients with HPV16-associated anogenital neoplasia is associated with restricted inability to recognize the disease-specific target cells, and may depend on persistence of the lesions.

Autocrine growth limitation of human papillomavirus type 16-harboring keratinocytes by constitutively released tumor necrosis factor-alpha

TNF-alpha is known to exert antitumor and antiviral effects and to participate in the regulation of the immune response. In our study we demonstrate that human rTNF-alpha specifically blocks growth of SK-v keratinocyte cell line harboring and expressing human papillomavirus type 16 (HPV16) sequences. This inhibitory effect was shown by [3H]TdR incorporation and cell counting. Binding experiments with 125I-TNF-alpha showed that SK-v cells express about 10,000 single class TNF-alpha R per cell with affinity constant of about 0.7 nM. Binding of 125I-TNF-alpha could be inhibited by htr-9 mAb recognizing a 55/60-kDa type I TNF-alpha R but not by utr-1 mAb recognizing 75/80-kDa type II TNF-alpha R or irrelevant mAb specific for HPV16E7 protein. Addition of anti-TNF-alpha antibodies to SK-v cell culture resulted in significant (p &lt; 0.05), dose-dependent stimulation of their proliferation. SK-v cells constitutively expressed TNF-alpha mRNA, and SK-v CM contained TNF-alpha, as demonstrated by Northern blot analysis, a specific ELISA, Western blot analysis, and a bioassay with TNF-alpha-sensitive L-M cells. HPLC gel filtration of SK-v cell CM showed that the factor cytotoxic for L-M cells coeluted with immunoreactive TNF-alpha. These results demonstrate that HPV16-harboring SK-v cells constitutively express and release immunoreactive and biologically active TNF-alpha that in turn may exert an autocrine growth inhibitory effect. This phenomenon could represent one of the self-limiting mechanisms controling growth of HPV-induced neoplasia.

Autocrine growth limitation of human papillomavirus type 16-harboring keratinocytes by constitutively released tumor necrosis factor-alpha

TNF-alpha is known to exert antitumor and antiviral effects and to participate in the regulation of the immune response. In our study we demonstrate that human rTNF-alpha specifically blocks growth of SK-v keratinocyte cell line harboring and expressing human papillomavirus type 16 (HPV16) sequences. This inhibitory effect was shown by [3H]TdR incorporation and cell counting. Binding experiments with 125I-TNF-alpha showed that SK-v cells express about 10,000 single class TNF-alpha R per cell with affinity constant of about 0.7 nM. Binding of 125I-TNF-alpha could be inhibited by htr-9 mAb recognizing a 55/60-kDa type I TNF-alpha R but not by utr-1 mAb recognizing 75/80-kDa type II TNF-alpha R or irrelevant mAb specific for HPV16E7 protein. Addition of anti-TNF-alpha antibodies to SK-v cell culture resulted in significant (p < 0.05), dose-dependent stimulation of their proliferation. SK-v cells constitutively expressed TNF-alpha mRNA, and SK-v CM contained TNF-alpha, as demonstrated by Northern blot analysis, a specific ELISA, Western blot analysis, and a bioassay with TNF-alpha-sensitive L-M cells. HPLC gel filtration of SK-v cell CM showed that the factor cytotoxic for L-M cells coeluted with immunoreactive TNF-alpha. These results demonstrate that HPV16-harboring SK-v cells constitutively express and release immunoreactive and biologically active TNF-alpha that in turn may exert an autocrine growth inhibitory effect. This phenomenon could represent one of the self-limiting mechanisms controling growth of HPV-induced neoplasia.

Late promoter of human papillomavirus type 8 and its regulation

Human papillomavirus type 8 (HPV8) belongs to the HPV types associated with skin carcinomas of patients with epidermodysplasia verruciformis (EV). Its noncoding regulatory sequences (NCR) were shown to drive the expression of the reporter gene chloramphenicol acetyltransferase (cat) in transient assays with human epithelial cells (HT3 cells). This constitutive activity could be enhanced by coexpression of the HPV8 transactivator protein E2. The analysis of 5' deletions of the NCR showed that the EV-specific sequence motif M33 and the neighboring AP1 site are essential for the promoter activity, whereas 44 nucleotides located immediately upstream of M33 are strongly inhibitory. The same effects were observed in simian virus 40-immortalized fetal keratinocytes (SV61 cells) and spontaneously immortalized skin keratinocytes (HaCaT cells). By using primer extension and RNase protection analyses two promoters could be identified within the HPV8 NCR. A nested set of weak signals, corresponding to start sites between positions 175 to 179, represented the previously described E6 promoter. The vast majority of transcripts was initiated at position 7535 and shown to undergo processing at an NCR-internal splice donor (positions 1 to 8). The promoter P7535 is similar to late promoters of other skin-associated papillomaviruses as far as localization, transcript structure, and sequence characteristics are concerned. To confirm that P7535-initiated transcripts proceed indeed to the L1 gene for the major capsid protein, viral mRNAs from an HPV8-induced lesion of a patient with EV were characterized by RNase protection and sequence analysis of polymerase chain reaction-amplified cDNAs. The NCR leader (positions 7535 to 4) appeared in two messages with three exons each. The third exon started with the second ATG codon of L1 in both cases; the short central exons from the 3' part of the early coding region were defined by a common splice acceptor site (position 3303) and different splice donor sites (positions 3443 and 3704).

Production of natural killer cell activity-augmenting factor (interleukin-6) by human epiphyseal chondrocytes

OBJECTIVE

We sought to determine the capacity of human epiphyseal chondrocytes to modulate the cytotoxic activity of human natural killer (NK) cells by determining whether they release interleukin-6 (IL-6), a cytokine recently shown to stimulate NK cell activity.

METHODS

Conditioned medium from human epiphyseal chondrocyte cultures (Ch-CM) was tested for IL-6 activity using the B9 cell hybridoma assay. Its NK cell-stimulating capacity in the presence of K562 (myelogenous leukemia) cells or human chondrocytes was evaluated in a 4-hour 51Cr-release assay. Ch-CM-derived IL-6/NK cell-augmenting factor activity was partially purified by high-performance liquid chromatography (HPLC) gel filtration and Western blot.

RESULTS

Ch-CM contained an NK cell-augmenting factor (NKAF) which was blocked by IL-2 or IL-6 antibodies. Ch-CM did not contain detectable IL-2 activity, but it stimulated IL-2 production by human peripheral blood lymphocytes (PBL). This IL-2-inducing capacity was inhibited by IL-6 antibodies, indicating that chondrocytes release an IL-6-like activity. Ch-CM significantly enhanced the proliferation of IL-6-dependent B9 hybridoma cells, and Western blot analysis of Ch-CM revealed specific bands corresponding to those of highly purified IL-6. Upon HPLC gel filtration, chondrocyte NKAF copurified with chondrocyte IL-6. Pure IL-6 and chondrocyte IL-6 were tested for their ability to stimulate the cytotoxic activity of human PBL against chondrocytes. Both mediators significantly enhanced chondrocyte killing. Lysis of chondrocytes by PBL was mediated by NK cells, since depletion of CD16+ cells resulted in inhibition of the activity.

CONCLUSION

Thus, upon stimulation, chondrocytes produce IL-6 which, through IL-2 induction, augments the activity of NK cells against K562 target cells as well as against chondrocytes.

Effect of immunosuppression on rejection of cartilage formed by transplanted allogeneic rib chondrocytes in mice

The effect of short-term immunosuppressive treatment with antithymocyte serum-procarbazine (ATS-PCH) and cyclosporin-A (Cy-A) on survival of allogeneic rib chondrocyte grafts was examined morphologically and by evaluation of specific humoral and cellular antigraft immunity. The latter were evaluated by means of leukoagglutination and the indirect migration inhibition assay, respectively. Untreated recipients of syngeneic rib chondrocytes and untreated recipients of whole syngeneic and allogeneic rib cartilage served as controls. Transplanted syngenic rib chondrocytes formed cartilaginous nodules similar to rib cartilage in situ. These nodules contained hypertrophied chondrocytes, but neither physiologic resorption by vascularized connective tissue nor bone formation occurred after an observation period of longer than six weeks. Transplantation of allogeneic chondrocytes resulted in development of humoral and cellular antigraft immunity, and the formed cartilage was destroyed by infiltrating immune cells. Immunosuppression by ATS-PCH resulted in inhibition of graft destruction and a marked decrease of specific humoral antigraft immunity. Cellular antigraft immunity did not occur. Moreover, neither the histologic appearance of the cartilaginous nodules nor the results of immunologic response evaluations in the ATS-PCH-treated group differed from those in untreated whole allogeneic cartilage recipients. Treatment with Cy-A did not significantly improve survival cartilage formed by allogeneic chondrocytes.

Constitutive release of IL6 by human papillomavirus type 16 (HPV16)-harboring keratinocytes: a mechanism augmenting the NK-cell-mediated lysis of HPV-bearing neoplastic cells

In the present study we demonstrate that the cultured human keratinocyte cell line (SK-v cells) harboring and expressing integrated human papillomavirus type 16 (HPV16) DNA sequences constitutively releases IL6, which is known as a pleiotropic immunoregulatory cytokine of potential antitumor properties. The presence of IL6 activity in SK-v cell-conditioned media (SK-v CM) was demonstrated by tritiated thymidine incorporation into IL6-dependent B9 murine plasmacytoma cells. The effect on B9 cells was specific since it could be inhibited by anti-IL6 neutralizing antibodies but not by a normal control serum. IL6 did not affect SK-v cell growth; however, it significantly augmented NK cell activity of human peripheral blood lymphocytes against both K562 erytholeukemic and SK-v cells as assessed by 51Cr release assay. SK-v CM displayed NK cell-augmenting activity that copurified with IL6 activity in both size exclusion and anion-exchange HPLC. Furthermore, SK-v cell-derived NK cell stimulatory activity could be neutralized with anti-IL6 antibodies. These results suggest that HPV-harboring neoplastic cells can release IL6 which may indirectly mediate tumor death by augmentation of NK cell activity.

[Studies on the production of epidermal cytokines after UVB irradiation in patients with epidermodysplasia verruciformis]

The production of interleukin-1 (IL-1) and interleukin-1 inhibitor by keratinocytes isolated from the skin of epidermodysplasia verruciformis patients was studied. Keratinocytes from uninvolved skin of patients with most pronounced neoplastic lesions produced large amounts of an IL-1 inhibitor (20-40 kD). Keratinocytes from preneoplastic lesions showed no significant differences compared to cells from healthy donors but their production of IL-1 after UVB irradiation was increased.

[Studies of natural killer cell cytotoxicity against human chondrocytes in patients with articular arthritic changes complicated by psoriasis and systemic scleroderma]

The natural killer (NK) activity against fetal chondrocytes was studied in patients with psoriasis and systemic sclerosis. It was shown that the cell responsible for the cytotoxic effect is a lymphocyte CD16+, CD2-. In patients with arthritic psoriasis NK activity against chondrocytes was significantly higher than in other psoriasis patients or in healthy controls. Preliminary studies show that the NK activity against chondrocytes is decreased in patients with systemic sclerosis.

Natural anti-chondrocyte cytotoxic activity in the mouse: supportive role of macrophages

The role of macrophages (M phi) in natural anti-chondrocyte cytotoxic activity of normal murine splenocytes (SPL) and peritoneal cells (PC) was examined by means of an 18-hr 51Cr-release assay. Removal of M phi by either plastic adherence or carbonyl iron and magnet resulted in significant (P less than 0.01) reduction of SPL-mediated lysis of chondrocytes. It, however, did not influence natural anti-YAC-1 leukemia activity. On the contrary, M phi-depleted suspensions of PC retained their anti-chondrocyte activity at the initial level. Neither adherent SPL nor adherent PC exerted significant anti-chondrocyte cytotoxicity. The activity of nonadherent SPL could be, however, restored by reconstitution with the graded numbers of syngeneic adherent spleen- or peritoneal cavity-derived cells. Restoration of anti-chondrocyte activity of nonadherent SPL to the level comparable with that of untreated SPL was achieved with about 10% of adherent cells. On the other hand, reconstitution of nonadherent PC did not result in an increase of chondrocyte lysis. Potentiation of nonadherent SPL activity was seen only with syngeneic M phi, and the latter could not be replaced by conditioned media which were generated in the 18-hr culture of adherent SPL or PC.

Natural cell-mediated cytotoxicity against various target cells in patients with epidermodysplasia verruciformis

Natural cell-mediated cytotoxicity of peripheral blood mononuclear cells was studied in eight patients with epidermodysplasia verruciformis induced by human papillomaviruses specific for epidermodysplasia verruciformis and in five patients with epidermodysplasia verruciformis-induced exclusively by human papillomavirus type 3. Nine patients with various cutaneous warts and 25 age- and sex-matched healthy persons were control subjects. Natural cell-mediated cytotoxicity against both K-562 erythroleukemic and Sk-v cells was in the normal range in patients with epidermodysplasia verruciformis induced by epidermodysplasia verruciformis-specific human papillomaviruses and in patients with cutaneous warts. The lysis of both targets, however, was significantly decreased in patients with the form of epidermodysplasia verruciformis associated with human papillomavirus type 3. Experiments with normal keratinocytes and with keratinocytes isolated from a malignant lesion bearing human papillomavirus type 5 genomes showed that the latter were susceptible to lysis by the peripheral blood mononuclear cells of healthy persons and of patients with cutaneous warts. Lysis of keratinocytes in epidermodysplasia verruciformis, however, was strongly reduced in patients with epidermodysplasia verruciformis induced by specific human papillomaviruses. This reduction was not associated with a decrease in anti-K-562 natural cell-mediated cytotoxicity. Our results suggest that in patients with epidermodysplasia verruciformis induced by disease-specific human papillomaviruses, there is reduced natural cell-mediated cytotoxicity against epidermodysplasia verruciformis keratinocytes.

Bone formation following intrarenal transplantation of isolated murine chondrocytes: chondrocyte-bone cell transdifferentiation?

Isolated syngeneic epiphyseal chondrocytes transplanted into a muscle formed cartilage in which matrix resorption and endochondral ossification began at the end of the second week after transplantation. After 56 days cartilage was converted into an ossicle. In 7-day-old intrarenal transplants, epiphyseal chondrocytes formed nodules of cartilage. In 10-day-old transplants, islands of bone appeared. Slight resorption of cartilage was first noted in 14-day-old transplants of chondrocytes. After eight weeks, transplants contained mainly bone. Intramuscularly transplanted rib chondrocytes formed cartilage which did not ossify. Nevertheless, bone islands appeared in intrarenal transplants of rib chondrocytes. Bone was not formed in allogeneic intrarenal transplants of epiphyseal or rib chondrocytes, but appeared in such transplants in animals immunosuppressed by anti-thymocyte serum and procarbazine. When spleen cells from animals immunized with allogeneic chondrocytes were transferred to immunosuppressed chondrocyte recipients two weeks after intrarenal chondrocyte transplantation, the majority of osteocytes in bone islands was dead. On the other hand, endochondral bone formed in intramuscular transplants of allogenic epiphyseal chondrocytes in immunosuppressed recipients was not damaged by sensitized spleen cells. This suggested that bone in 10- to 14-day-old intrarenal transplants of chondrocytes arose from injected cells and not by induction. To see whether bone was formed by chondrocytes or by some cells contaminating the chondrocyte suspension, the superficial layer of rib cartilage was removed by collagenase digestion and only more central chondrocytes were used for transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

IFN-beta 2/IL-6 augments the activity of human natural killer cells

MHC nonrestricted cytotoxic cells play an important role in the killing of tumor cells in vitro and potentially in vivo. The activity of these cells is regulated by several cytokines such as IL-2 and IFN. In the present study we provide first evidence that IL-6 significantly augments the cytotoxic activity of human NK cells. IL-6 is produced by many different cells and is also known as IFN-beta 2, B cell stimulatory factor 2, hybridoma growth factor, hepatocyte-stimulating factor, and 26 kDa protein. IL-6 stimulates the activity of human CD3- NK cells but not that of CD3+ non-MHC-restricted cytotoxic T lymphocytes. As is the case with IL-2, the IL-6-mediated augmented cytotoxicity was a result of a more efficient lysis, but was not caused by an increased effector to target cell binding. Moreover, the effect of IL-6 on NK cell activity was blocked by a mAb directed against IL-2, and IL-6 itself was found to be a potent inducer of IL-2 production in cultured human PBMC. Thus it may be concluded that IL-6 enhances the cytotoxic activity of NK cells via IL-2. This newly recognized property of IL-6, which is produced by almost any cell, may be of importance in host defense against microbes and malignancies and therefore could contribute to improve the adoptive immunotherapy by using lymphokine-activated killer cells.

IFN-beta 2/IL-6 augments the activity of human natural killer cells

MHC nonrestricted cytotoxic cells play an important role in the killing of tumor cells in vitro and potentially in vivo. The activity of these cells is regulated by several cytokines such as IL-2 and IFN. In the present study we provide first evidence that IL-6 significantly augments the cytotoxic activity of human NK cells. IL-6 is produced by many different cells and is also known as IFN-beta 2, B cell stimulatory factor 2, hybridoma growth factor, hepatocyte-stimulating factor, and 26 kDa protein. IL-6 stimulates the activity of human CD3- NK cells but not that of CD3+ non-MHC-restricted cytotoxic T lymphocytes. As is the case with IL-2, the IL-6-mediated augmented cytotoxicity was a result of a more efficient lysis, but was not caused by an increased effector to target cell binding. Moreover, the effect of IL-6 on NK cell activity was blocked by a mAb directed against IL-2, and IL-6 itself was found to be a potent inducer of IL-2 production in cultured human PBMC. Thus it may be concluded that IL-6 enhances the cytotoxic activity of NK cells via IL-2. This newly recognized property of IL-6, which is produced by almost any cell, may be of importance in host defense against microbes and malignancies and therefore could contribute to improve the adoptive immunotherapy by using lymphokine-activated killer cells.

Natural cell-mediated cytotoxicity against syngeneic rat chondrocytes originating from different types of cartilage

Natural anti-chondrocyte cytotoxicity of normal rat splenocytes, peritoneal cells and thymocytes was tested by means of 51Cr-release assay. Chondrocytes derived from epiphyseal, costal, nasal, and auricular cartilages were used as target cells. In some experiments, erythroleukaemic K-562 cells, known as typical natural killer cell targets, were also used. All types of chondrocytes were lysed equally well by splenocytes. Peritoneal cells exerted a low cytotoxic effect, whilst very low, almost negligible, cytotoxicity was noted with thymocytes. Negative selection with antibodies and complement showed that spleen-derived anti-chondrocyte effector cells are endowed with surface ganglioside asialo-GM1. A similar result was obtained in parallel experiments with K-562 cells. Moreover, 'cold' target experiments demonstrated that the release of 51Cr from the labelled chondrocytes could be inhibited by addition of unlabelled chondrocytes and K-562 cells.

Reactivity of normal rat epiphyseal chondrocytes with monoclonal antibodies recognizing different leucocyte markers

The aim of the study was to test whether normal rat epiphyseal chondrocytes react with monoclonal antibodies (MoAbs) detecting different markers of lymphoid cells. For this purpose, isolated chondrocyte and, for comparison, splenocyte cytosmears were exposed to a battery of different MoAbs followed by indirect immunoperoxidase staining. As we were able to show, all chondrocytes reacted with OX17 MoAb detecting Class II (Ia) antigen encoded by the RT1.D subregion of rat major histocompatibility complex (MHC). However, unlike splenocytes they did not react with OX6 MoAb detecting the RT1.B encoded Class II molecule. Moreover, all chondrocytes were stained with W3/25 MoAb specific for the rat equivalent of human CD4 (T4) antigen and with W3/13 MoAb specific for rat leucocyte sialoglycoprotein. A positive reaction was also obtained with the antibody against the S-100 protein. By contrast, chondrocytes did not react with antibodies specific for all T (OX19) or B (HIS14) cells, rat CD8 (T8) equivalent, monocytes/macrophages (ED1, ED2), factor VIII (M616), or glial fibrillary acidic protein (Z334).

Abrogated NK-cell lysis of human papillomavirus (HPV)-16-bearing keratinocytes in patients with pre-cancerous and cancerous HPV-induced anogenital lesions

Natural-cell-mediated cytotoxicity against K-562 erythroleukemic cells and human papillomavirus (HPV)-16 harboring Sk-v keratinocytes was tested in 38 age- and sex-matched healthy volunteers and in patients with HPV-induced benign and malignant anogenital lesions: 9 persons with HPV-16-induced bowenoid papulosis (BP), 8 with anogenital carcinomas (5 with HPV-16- or 33-associated squamous-cell carcinomas of Bowen's type and 3 with HPV-6-associated Buschke-Loewenstein verrucous carcinomas) and 12 with HPV-6-induced condylomata acuminata. Both K-562 and Sk-v cells were killed by a non-adherent CD16+ subset of PBMC as revealed by cell fractionation on the basis of their adherence to plastic and by treatment with Leu-IIb monoclonal antibody (MAb) and complement. "Cold" target competitive assays demonstrated that both cell types inhibited lysis of labelled Sk-v cells. In patients with BP and anogenital carcinomas induced by HPV-16 or 33, there was a significant (at least at p less than 0.01) decrease of Sk-v cell lysis as compared with the healthy control group. Anti-K-562 activity was not affected. In patients with anogenital carcinomas the degree of Sk-v lysis was decreased in proportion to the duration of lesions (correlation coefficient-r = -0.79). Neither anti-K-562 nor anti-Sk-v cytotoxicities were significantly affected in patients with condylomata and with HPV-6 associated verrucous carcinomas. Short-term (3 hr) pre-incubation of normal PBMC with sera from patients with BP and HPV-16-associated anogenital carcinomas resulted in significant inhibition of their ability to lyse Sk-v cells. Lysis of K-562 cells remained unaffected. In patients with carcinomas, the suppressive effect of sera was associated with a lowering of the ability of their PBMC to lyse Sk-v cells (r = -0.79). In patients with longer tumor persistence, the suppressive effect of serum was proportionally higher (r = 0.86).

Natural anti-chondrocyte cytotoxicity of normal human peripheral blood mononuclear cells

Natural cytotoxic activity of peripheral blood mononuclear cells (PBMC) from healthy humans against normal epiphyseal chondrocytes was assessed in the 51Cr-release assay. PBMC lysed human fetal chondrocytes, while exerting only low activity against xenogeneic rat chondrocytes. Anti-human chondrocyte cytotoxicity was also demonstrated with normal human splenocytes. Peripheral blood anti-chondrocyte effector cells were shown to be plastic nonadherent and nonphagocytic. Cell separation by sheep red blood cells rosette sedimentation has revealed that most of the anti-chondrocyte activity was found in the T cell-depleted fraction. Only a low activity was present in the T cell-enriched fraction. Depletion of cells endowed with receptor for the Fc portion of the IgG molecule by either IgG-coated ox red blood cells rosette sedimentation or treatment with natural killer (NK) cell-specific anti-Leu-11b monoclonal antibody and complement resulted in almost complete elimination of cells responsible for chondrocyte lysis. Short-term (3-hr) preincubation of PBMC with interferon-alpha strongly augmented their anti-chondrocyte cytotoxicity. On the other hand, no stimulation of chondrocyte lysis was seen after a 3-hr preincubation with interleukin 2 although this treatment increased significantly NK cell-mediated lysis of K-562 leukemic cells. Using competitive assay it has been demonstrated that 51Cr-labeled chondrocyte lysis can be inhibited by addition of "cold" human chondrocytes as well as by cold K-562 cells. Only low inhibition of lysis was seen with cold xenogeneic rat chondrocytes. All these results show that natural anti-chondrocyte effectors share phenotypic and functional properties with typical NK cells.

Effect of immunosuppression on survival and growth of cartilage produced by transplanted allogeneic epiphyseal chondrocytes

Strong short-term immunosuppression improved survival of cartilage formed by transplanted allogeneic epiphyseal chondrocytes in mice. The agents tested were cortisone acetate (CA), cyclophosphamide (CY), procarbazine (PCH), and antithymocyte serum (ATS). Their effect on syngeneic grafts was examined morphologically and histomorphometrically. In untreated recipients, chondrocytes formed cartilage nodules that underwent endochondral ossification. Except for high repetitive doses of CY, none of the other agents interfered with normal cartilage formation. However, all agents affected endochondral ossification. In the allogeneic system, the effect of immunosuppression was examined morphologically and by evaluation of specific humoral and cellular antigraft immunity. Allogeneic chondrocytes evoked a strong immune response in untreated mice, and cartilage was gradually destroyed by infiltrating cells. Endochondral ossification did not occur in this system. Neither agent given alone exerted a marked, long-lasting protective effect upon the graft. However, combined treatment with ATS and PCH inhibited immune response and completely prevented infiltrate formation and allowed endochondral ossification similar to that in the syngeneic control. Although some weak signs of antigraft immunity were seen after six weeks, it is possible that they were due to secondary exposure of antigen-bearing chondrocytes in the course of endochondral ossification.