Association of HLA class I and class II antigen expression and mortality in uveal melanoma

Purpose. Malignant transformation of cells is frequently associated with abnormalities in human leukocyte antigen (HLA) expression. These abnormalities may play a role in the clinical course of the disease, because HLA antigens mediate interactions of tumor cells with T cells and NK cells. Uveal melanoma is a highly malignant tumor of the eye and is characterized by a hematogenic spread to the liver. Little is known about the role of HLA expression in progression of this malignant disease. Methods. In the present study HLA class I antigen, β₂-microglobulin (β₂-m), and HLA class II antigen expression was analyzed in primary uveal melanoma lesions by immunoperoxidase staining with monoclonal antibodies of 65 archival clinical samples. The results were correlated with the clinical course of the disease. Results. HLA class I antigen expression and β₂-m expression were downregulated in 40 and 35 lesions, respectively. HLA class II antigens were expressed in 30 lesions. Patients with high HLA class I, including β₂-m, and HLA class II antigen expression in their primary melanoma lesions had a significantly decreased survival (P = 0.009, P <0.001, and P = 0.006, respectively). Conclusions. The findings argue against a major role of cytotoxic T-lymphocyte (CTL)-mediated control of tumor growth in the clinical course of uveal melanoma and are compatible with a potential role of NK-cell-mediated control of hematogenic metastatic spread.