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Background: The level of HLA expression on a tumour may influence the immunological response against this tumour, and vice versa. HLA expression was determined in a primary uveal melanoma, its metastases, and on a cell line derived from this melanoma, and the presence and type of infiltrate in tissue sections were also studied., Methods: Immunohistochemistry with monoclonal antibodies (MAbs) against HLA class I and II, T cells, NK cells, and macrophages., Results: Primary and metastatic lesions, as well as the cell line showed high levels of expression of the monomorphic determinants of HLA class I. Expression of the polymorphic HLA-A2 and HLA-A3 antigens was decreased on metastases to the skin and liver. HLA-Bw4 expression was low on all lesions, as well as expression of HLA class II. Tumour infiltrating cells consisted mainly of CD3, CD4, and CD8 positive cells. Expression on the cell line corresponded to expression on the primary tumour., Conclusion: The primary uveal melanoma as well as the cell line showed a high expression of monomorphic and polymorphic HLA-A antigens, while metastases showed a high expression of monomorphic and a lower expression of polymorphic antigens. This variation in expression may support tumour cell escape from NK cells as well as CTL mediated lysis.

Background: Uveal melanoma is a tumour with a high incidence of metastasis and a high mortality rate. Additional therapies to obtain a better local control or an effective treatment of metastases are necessary. Interferons may be applied., Methods: The effects of human interferon alfa and gamma on proliferation and expression of immunologically important molecules of human uveal melanoma cells in vitro were studied. A propidium iodide assay was used to determine proliferation and immunostaining with monoclonal antibodies was applied to detect changes in antigen expression on two primary uveal melanoma cell lines, Mel 202 and 92-1., Results: Interferon alfa inhibited proliferation of cell line 92-1 at a concentration of 50 IU/ml, but had no effect on cell line Mel 202, while interferon gamma inhibited growth of both cell lines. Only interferon gamma had a visible effect on cell morphology. With respect to the immunomodulatory effects, interferon alfa increased monomorphic HLA class I expression, but did not affect HLA class II expression. Interferon gamma induced not only HLA class I but also class II expression. The effects on HLA expression were locus-specific with the strongest effects observed for HLA-B and DR products. Small differences were observed with respect to the susceptibility of two different melanoma cell lines to antiproliferative effects and to modulation of antigen expression., Conclusion: The effects of interferon alfa and gamma on human uveal melanoma cells in vitro suggest a potential role of these cytokines in the treatment of patients with uveal melanoma. In particular, the immunomodulatory effects of these cytokines in vitro imply that treatment of patients with these cytokines might stimulate a beneficial antimelanoma immune response in vivo.