Anti-T antibody in malignant melanoma patients. Influence of response and survival following chemotherapy--changes in serum levels following C parvum, BCG immunization.

The level of anti-T antibodies directed towards the precursor T antigen of the MN blood group system was measured in the sera of 55 patients with disseminated melanoma, before and during chemoimmunotherapy. The anti-T titer was subnormal in patients before therapy; patients who responded to therapy had significantly higher titers than did nonresponders in sera taken before therapy, at regression/progression of disease, and during the last pulse of treatment. Higher pretreatment titers were associated with a significntly longer survival time. A single infusion of Corynebacterium parvum was given to 14 other melanoma patients and significant elevation of preimmunization titers was observed on days 14, 21, and 28 after infusion; Bacillus Calmette-Guerin, vaccination of 9 patients did not significantly alter the anti-T titer. The expression of the normally cryptic T antigen on melanoma cells would absorb naturally circulating anti-T antibodies. Less dense expression of T antigen on melanoma cells that were responsive to therapy, i.e., less "malignant," would explain the better prognosis for patients with higher titers. The increase in anti-T antibodies following administration of C parvum but not of BCG is of possible clinical relevance when C parvum is used as an immunotherapeutic agent.