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 2½ 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.