Clinical and laboratory changes induced by alpha interferon in chronic lymphocytic leukemia--a pilot study.

Ten chronic lymphocytic leukemia patients were treated with partially pure alpha interferon (IFN-alpha) at doses ranging from 3-9 X 10(6) units administered intramuscularly daily. Of these patients, three patients with disease stages 0, 1, and 3 (and prolymphocytic leukemia), respectively, responded with partial remissions lasting from 10 to 24+ months; four additional patients had minor responses. Among those responding, modulation of B cell chronic lymphocytic leukemia, surface immunoglobulins, and surface antigens were observed in four patients. These changes included a decline in the proportion of B cells bearing surface immunoglobulin without change in the number of the B cells. Likewise, a decline in the proportion of B cells bearing T-1 antigen was observed in three patients. Increase in the percentage of T cells, primarily the T helper cells, was seen in two of the responding patients. Specific binding of alpha interferon was demonstrated prior to therapy in CLL cells of all patients. This binding declined rapidly following treatment with IFN-alpha. Induction of the enzyme 2'5' oligoisoadenylate synthetase was examined in CLL patients prior to and during therapy with IFN-alpha. Variable levels of the enzyme were induced in all patients on therapy; however, only minimal induction was observed in two of three patients failing therapy.