Uveal melanomas contain antigenically specific and non-specific infiltrating lymphocytes

Tumor-infiltrating lymphocytes (TIL) were recovered from a series of human choroidal melanomas and expanded in cultures containing interleukin-2 (IL-2) to determine whether TIL contained cytotoxic cells that could be activated in vitro.

TIL were recovered from six ocular melanoma patients and expanded in vitro with IL-2. 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. HLA class I expression on tumor cells was determined by flow cytometry.

TIL from four patients lysed autologous ocular melanoma cells. Two of these patients possessed TIL that displayed specific cytotoxic activity and failed to lyse tumor cells from other patients (HLA-mismatched, or -matched). TIL from the remaining two patients possessed non-specific cytotoxic cells that lysed ocular melanoma cells from a variety of other patients (HLA-mismatched). 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.