Abstract
Peripheral blood lymphocytes from 32 patients with malignant melanoma were tested for cellโmediated cytotoxicity (CMC) against cultured autologous melanoma cells. Effector cells were prepared from venous blood by defibrination, gel sedimentation, nylon column filtration, and lysis of remaining erythrocytes with NH~4~Cl. Melanoma cells prelabelled with [^3^H]proline were used as target cells in a 40โh assay and CMC was evaluated against standards obtained with blood lymphocytes from the least reactive normal donor. Reproducible autologous CMC was detected in 18 of 32 patients in a series of 367 total tests. CMC correlated with tumor volume (5โ500 cm^3^) but not with tumor stage or DNCB reactivity. Preliminary results indicated that autologous CMC was not affected by treatment with DTIC, dexamethasone, intralesional BCG, radiation therapy, or partial surgical excision. Lack of consistent CMC in 14 patients could not be attributed to a measurable decrease in general immune capacity or to increased resistance of the patients' melanoma cells to CMC in general. Fibroโblasts were more resistant to CMC than melanoma cells, and therefore of questionable value for defining specificity in direct tests.