Leukocyte interferon-induced myeloid cytoreduction in chronic myelogenous leukemia.

We investigated the antiproliferative effect of partially purified human leukocyte interferon (HuIFN-alpha) given in a dose of 9-15 X 10(6) U daily by intramuscular injection to 7 patients with chronic myelogenous leukemia (CML). Hematologic remission of the disease was obtained in 5 patients. Among the responding patients, the mean white blood cell count decreased from 97.4 X 10(3)/cu mm (range from 35 X 10(3)/cu mm to 239 X 10(3)/cu mm) to 4.2 X 10(2)/cu mm (range from 3.0 X 10(3) to 7.9 X 10(3) cu/mm). Parallel reduction occurred in serum B12, from a mean of 1,435 pg/ml to a mean of 726 pg/ml, and lactate dehydrogenase levels, from a mean of 325 mU/ml to 112 mU/ml. Enlarged spleens decreased in 3 of 3 patients. The 5 responding patients have been maintained on HuIFN-alpha, 3 X 10(6) U daily or every other day, for 6+-35+ wk.