Interleukin-2 corrects defective NK activity of patients with leukemia

NK cells of patients with leukemia display low cytotoxic potential. Since the NK cells have been suggested to play a role in natural resistance to leukemia, we considered it of importance to investigate the approaches leading to the correction of NK defect of leukemic patients. Our studies demonstrate that culture of effector cells with interleukin-2 (IL-2) resulted in restoration of cytotoxic defect. This was indicated by normalization of tumor-binding as well as lytic NK activity, by normal frequency of cytotoxic cells and their ability to recycle. The NK cell nature of cytotoxic cells was shown by abrogation or depletion of cytotoxicity by antibody directed against NK cell-associated, but not T cell-associated antigen. The generation of NK cell activity against fresh leukemic cells suggests that adoptive transfer of IL-2 activated NK cells may be a new approach to leukemic treatment.