Effect of in vivo administration of interferon gamma on expression of MHC products and tumour associated antigens in patients with metastatic melanoma.

Abstract

IFN-gamma is an effective inducer of MHC class II antigen expression in cell lines of malignant melanoma. To investigate the possibility that IFN-gamma may increase MHC class I and II and melanoma tumour associated antigens in vivo, immunohistochemical analyses of biopsies from six patients with metastatic disease undergoing IFN-gamma treatment were performed. Before IFN-gamma treatment, the melanomas were class I positive and class II negative. After treatment, class I expression was neither enhanced nor class II expression induced in any tissue sample regardless of biopsy time or dose of IFN-gamma. TAA was similarly unchanged. However, in one of the six patients a primary cell line was established and IFN-gamma induced expression of MHC products. The possible reasons for lack of MHC induction are discussed, although qualitative changes in antigen expression cannot be excluded on the basis of qualitative immunocytochemical techniques alone.