hla expression in a primary uveal melanoma its cell line and four of its metastases 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 studiedmethods immunohistochemistry with monoclonal antibodies mabs against hla class i and ii t cells nk cells and macrophagesresults 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 hlaa2 and hlaa3 antigens was decreased on metastases to the skin and liver hlabw4 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 tumourconclusion the primary uveal melanoma as well as the cell line showed a high expression of monomorphic and polymorphic hlaa 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