Antibody responses of remission leukemia patients receiving active specific and nonspecific immunotherapy.

A solid-phase radioimmunoassay was utilized to evaluate the antibody response of 21 acute myelogenous leukemia (AML) patients to active specific immunotherapy with either pooled allogeneic AML blast cells or leukemia-associated antigen (LAA), admixed with BCG cell-wall skeleton (CWS). Five of 13 patients treated with LAA had a significant antibody response to LAA after immunotherapy. Antibody response correlated with an increased remission duration (159+ vs. 75+ weeks) and an increased survival (164+ vs. 98+ weeks). Two of eight patients treated with cells responded to LAA, and three patients had initially high anti-LAA antibody levels. In the total study, eight of 11 patients surviving longer than 2 1/2 years and six of seven patients maintaining a complete remission longer than 2 years were antibody responders. Neither protocol induced significant antibody to a normal spleen extract, BCG-CWS, or a measles recall antigen. However, five of seven patients with initially high levels of antibody to BCG (following weekly BCG scarification) were long-term survivors. These data suggest that the humoral immune response to immunotherapeutic agents may be a useful parameter for monitoring immunotherapy of AML patients.