Cytotoxicity of lymphocytes from healthy subjects and from melanoma patients against cultured melanoma cells.

The in vitro cytotoxicity of lymphocytes from forty-seven melanoma patients and thirteen healthy subjects for cultured melanoma cells was studied using a 51Cr release assay. Two different melanoma cell lines were used as target cells: one cultured in suspension (SK Mel1) and one tissue culture line growing as a monolayer (NK I1). The lymphocytes from most healthy subjects were found to be cytotoxic for these cultured cells, with individual variations. These repeatable cytotoxic reactions could not be explained on the grounds of previous isoimmunization. The lymphocytes from melanoma patients were also cytotoxic for the melanoma cell lines, but the highest degree of cytotoxicity was found in patients with primitive and localized tumours, and not in patients with metastases.