Destruction of cultivated melanoma cells by lymphocytes from healthy Black (North American Negro) donors

Peripheral blood lymphocytes from healthy Black (North American Negro) donors were found to be cytotoxic to cultivated malignant melanoma cells (7 out of 9 tested), but not to tumor cells of other types or to normal skin fibroblasts, in experiments using lymphocytes from normal White donors and from White patients with other types of tumor as controls. Lymphocytes from normal Blacks thus behaved similarly to lymphocytes from patients having melanomas. The cytotoxic effect could be blocked by sera from patients with progressively growing melanomas. Sera from some healthy Black donors could abrogate (“unblock”) the blocking effect of sera from patients with growing melanomas (four out of four tested).