Cytotoxic activity was tested in a standard 4-hr 51Cr release assay. The HLA class I phenotype of patients was determined, using peripheral blood lymphocytes and the Amos modified-cytotoxicity test. I expression on tumor cells was determined by flow cytometry. TIL from four patients lysed autologous ocular melanoma cells. TIL from patients that failed to lyse autologous tumor cells possessed cytotoxic activity for ocular melanoma cells from other HLA- mismatched patients.
Ocular melanomas accumulate lymphocytes with the potential to kill tumor cells.
Our results imply that elimination of tumor cells may be possible by activation of cytotoxic cells present within progressively growing ocular tumors. DNA from peripheral blood lymphocytes and fresh frozen or paraffin-embedded tumor tissue from 19 patients was amplified by the polymerase chain reaction for polymorphic loci on chromosome 3, including dinucleotide repeats, a tetranucleotide repeat, and polymorphic restriction enzyme sites. Three tumors showed LOH at multiple informative loci on both short and long arms of chromosome 3. Two additional tumors showed localized LOH on 3q, which corresponded to large deletions seen by cytogenetic analysis. The remaining 16 tumors showed retention of heterozygosity at all informative loci.