HLA EXPRESSION IN A PRIMARY UVEAL MELANOMA, ITS CELL-LINE, AND 4 OF ITS METASTASES

Background-The level of HLA expression on a tumour may influence the i mmunological response against this tumour, and vice versa. HLA express ion 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-Immunohistoch emistry with monoclonal antibodies (MAbs) against HLA class I and II, T cells, NK cells, and macrophages. Results-Primary and metastatic les ions, as well as the cell line showed high levels of expression of the monomorphic determinants of HLA class I. Expression of the polymorphi c HLA-A2 and HLA-A3 antigens was decreased on metastases to the skin a nd Liver. HLA-Bw4 expression was low on all lesions, as well as expres sion of HLA class II. Tumour infiltrating cells consisted mainly of CD 3, CD4, and CD8 positive cells. Expression on the cell line correspond ed to expression on the primary tumour. Conclusion-The primary uveal m elanoma as well as the cell line showed a high expression of monomorph ic and polymorphic HLA-A antigens, while metastases showed a high expr ession of monomorphic and a lower expression of polymorphic antigens. This variation in expression may support tumour cell escape from NK ce lls as well as CTL mediated lysis.