Expression pattern of HLA class I antigens in renal cell carcinoma and primary cell line cultures: methodological implications for immunotherapy.

BACKGROUND: Renal cell carcinomas have developed various strategies to escape immune cell recognition, including down-regulation or loss of classic HLA class I antigens (A, B, C) and aberrant expression of non-classic HLA class I antigens (G, E). In this study both classic and non-classic HLA class I antigens were tested in tumor specimens and established primary cell cultures derived from renal cell carcinoma patients. MATERIAL/METHODS: HLA class I antigens were evaluated by immunohistochemical staining and the intensity of cytoplasmic staining was measured semiquantitatively. Renal tumor tissue obtained from nephrectomy was used for the explant culture. MTT assay was performed to test the chemoresistance of primary cell line cultures to common cytostatics. RESULTS: HLA-G and HLA-E were found in 62% and 100% of the analyzed tumor samples, respectively. Markedly higher levels of the non-classic HLA-G and -E antigens compared with the classic HLA-A, -B, and -C antigens were observed. The cells of the control renal tissues were HLA-A, -B, -C, and -E positive and HLA-G negative. Cell line cultures were successfully established in 85% of the renal cell carcinoma specimens. No or minimal changes in classic HLA-A, B, and C antigen staining were observed during cultivation of the primary cell line cultures. No correlation between HLA class I antigen expression and chemoresistance, histopathological stage, or nuclear grade was found. CONCLUSIONS: These findings suggest that primary cell line cultures derived from surgical specimens of renal cell carcinomas are a feasible model for immunotherapy research through their high cultivation potential.

Interferon-gamma, but not interferon-alpha, induces SOCS 3 expression in human melanoma cell lines.

The signal transducers and transcription activators (STATs) and their endogenous inhibitors of the suppressors of cytokine signalling (SOCS) family are major proteins harmonizing the transmission of external signals from the surface membrane to target genes in the nucleus. To correlate the induction of SOCS 3 by interferons (IFNs) on messenger RNA and protein levels with STAT 1 phosphorylation in human malignant melanoma cell lines, we used a unique collection of 18 established malignant melanoma cell lines and six human non-malignant normal cells (two melanocytes, two skin keratinocytes and two fibroblasts). IFN-gamma induced SOCS 3 in 83% of melanoma cell lines, whereas IFN-alpha stimulated SOCS 3 expression in only 11% of cases. Similarly, melanocytes showed strong induction of SOCS 3 by IFN-gamma and, to a lesser extent, by IFN-alpha. In most cases, SOCS 3 expression was paralleled by STAT 1 phosphorylation at tyrosine residues (Y701). In several lines, however, SOCS 3 was not induced despite STAT 1 phosphorylation and, in a few lines, SOCS 3 induction occurred without detectable STAT 1 phosphorylation, indicating that STAT 1 might not be an exclusive inducer of SOCS 3. Similarly, non-malignant cells displayed STAT 1 activation and high levels of SOCS 3 expression after IFN-gamma (but not IFN-alpha) treatment. In conclusion, in contrast to IFN-alpha, IFN-gamma appeared to induce SOCS 3 apparently at the transcription level and exhibited higher cytotoxic effects regardless of the cell origin.