SPONTANEOUS REMISSION OF ACUTE MYELOID-LEUKEMIA AFTER INFECTION AND BLOOD-TRANSFUSION ASSOCIATED WITH HYPERGAMMAGLOBULINEMIA

Spontaneous remissions of acute myeloid leukemia (AML) have been docum ented in association with infection as well as blood transfusions. Act ivation of the immune system including an increased number of NK cells and cytokine release have been implicated in the mechanism of this ph enomenon. We have observed spontaneous remissions in two patients with AML (one with a t(8;21)-positive M2, one with M5b), both occurring af ter infection and blood transfusions. The bone marrow showed a reducti on of blast cells from 65% to 2% or 40% to 1%, respectively. Remis sio n was accompanied by a marked polyclonal hypergammaglobulinemia in bot h cases (IgG values of 6420 and 2160 mg/dl, IgA of 802 and 811 mg/dl, respectively). A concomitant increase in bone marrow plasma cells was observed in both patients, Reduction of AML1/ETO PCR positivity from o ne-step to two-step PCR (approximately 100-fold) was documented in the patient with a t(8;21), while a regression of lymph node and skin leu kemic infiltrations occurred in the patient with M5b. One patient rela psed after 4 months, at a time when his serum immunoglobulin levels ha d markedly decreased. The other patient is in continuous remission aft er 14 months. These cases suggest a potential role for a humoral immun e response in the mechanism of spontaneous remission.