Killing effect of interleukin-2 and interferon-alpha activated leukemic bone marrow in remission on K562 leukemic cells

Objective To evaluate the killing effect of interleukin-2 (IL-2) and interf eron-alpha (IFN-alpha) activated bone marrow cells on K562 cells. Methods Semi-solid colony and H-3-TdR incorporating method were used. Results Bone marrow from leukemia patients in remission was activated in vi tro with IL-2 for 3 days. The activated bone marrow (ABM) displayed killing effects of 0.31-2.30 logs on K562 cells. This killing effect was further i ncreased to 0.30-3.15 logs when IFN-alpha added with IL-2 to the marrow for activation. IL-2 alone or in combination with IFN-alpha showed no inhibiti on of CFU-GM and K562 cells. Compared with IL-2 or IFN-alpha alone, the com bination of the two cytokines could more effectively maintain the killing e ffect of ABM on leukemic cells. Conclusions IFN-alpha can augment the purging effect of IL-2 ABM and combin ation of the two cytokines can effectively maintain the cytotoxicity of ABM .