Immunotherapy versus chemotherapy of acute myeloid leukemia: response to PHA, allogeneic lymphocytes, and leukemic myeloblasts of remission lymphocytes from leukemia patients.

Lymphocytes were studied from 51 patients with acute myeloid leukemia (AML) in remission given chemotherapy (CT) maintenance alone or given chemoimmunotherapy (CIT) with BCG and viable allogeneic leukemic cells. CT lymphocytes reacted significantly more to PHA (P less than 0.05) if taken later than 100 days after remission than if taken earlier. CIT lymphocytes reacted less. Thus, the late CT lymphocytes reacted significantly more to nonspecific stimulators (PHA and allogeneic lymphocytes, P less than 0.01) than did late CIT lymphocytes or control lymphocytes. In consequence, the ratio of reactions to specific (leukemic myeloblasts) over nonspecific stimulators was significantly higher in CIT (P less than 0.01) than in CT lymphocytes. Results may indicate nonspecific immunostimulation during CT, and also some relative specific sensitization to allogeneic myeloblasts during CIT.