Immunotherapy of human acute leukemia: antibody response to leukemia- associated antigens

We studied the hormonal antibody response to leukemia-associated antigens in patients with acute myeloblastic leukemia (AML) receiving immunotherapy and examined the relationship of antibody production to patient survival.Sixteen adult patients with AML in complete remission were given weekly immunotherapy in addition to monthly remission maintenance chemotherapy.Immunotherapy consisted of intradermal injection of both BCG and irradiated allogeneic leukemic blast cells.The cells for injection were obtained from a single donor for each patient.Sera from the vaccinated patients were studied for reactivity with a panel of leukemic blast cells using complement-mediated cyto-toxicity and indirect im munofluorescence techniques.Following 4-6 wk of immunotherapy, sera from 10 of 16 patients developed anti-blast cell reactivity.Activity was significantly greater against myeloblasts than against other leukemic or nonleukemic peripheral blood cells (p < 0.001).Of the 10 patients with anti-blast cell activity, 6 had demonstrable activity against alloantigens as well, but the two activities could be separated by reciprocal absorptions.Four sera with anti-blast cell activity showed no reactivity with either HIA or B cell alloantigens.An antibody response directed against leukemiaassociated antigens may occur in patients with AM I receiving immunotherapy.