In vivo evaluation of cell mediated immunity against human melanoma

Evaluation of cell mediated immunity against human melanoma target cells was performed in an in vivo model using human tumor xenografts growing in Balb/c athymic mice. Intraperitoneal inoculation of 1 x 10(7) human melanoma cells produced carcinomatosis which lead to death of the animals at 23.8 +/- 2.6 days (N = 12). Peripheral blood lymphocytes (PBL) from normal donors were administered to tumor bearing mice, and survival times of 22.0 +/- 2.3 days were observed (N = 8). Peripheral blood lymphocytes from the four of five normal donors which had been presensitized on monolayers of melanoma tissue culture cells in vitro failed to prolong host survival times. In contrast, PBL obtained from 15 or 20 melanoma patients were found to prolong survival of the tumor bearing nude mice. Of these 15 patients, 8 were undergoing specific active immunotherapy, while 7 had not been sensitized except by the disease process. The ability of PBL obtained from patients to prolong survival of tumor bearing animals did not appear to correlate with either the stage of the disease or the patient's clinical course. The possible mechanisms for the prolonged survival and usefulness of this model are discussed.