Response of therapy-related myelodysplasia to low-dose interleukin-2.

We report the case of a patient treated with interleukin-2 (IL-2) for refractory anemia with excess blasts (RAEB), which developed during third complete remission of acute lymphoblastic leukemia. IL-2 was given subcutaneously at 2.5 x 10(5) IU (= 10(5) BRMP units) twice daily for 30 days. During treatment spontaneous natural killer (NK) activity was enhanced, circulating lymphokine-activated killer effector cells became detectable and CD56+/CD3- NK cells in the blood doubled. The response in the bone marrow was a reduction in myeloid blast cells (from 7 to 0%), ringed sideroblasts (from > 15 to 0%) and dysplasia (from trilineage to minimal megakaryocytic), and a decrease in metaphases with the RAEB karyotype (from 43 to 2%). Toxicity of IL-2 was minimal. Thus a relatively low dose of IL-2 caused immune activation and resulted in significant hematologic and cytogenetic response in this case of therapy-related myelodysplasia.