Immunologic and clinical aspects of natural killer cells in human leukemia.

We have studied peripheral-blood, splenic and bone marrow natural killer (NK) activity in patients with leukemia. These studies demonstrated that leukemic patients displayed defective NK activity in all of these tissues. However, NK defect could be corrected by culture of effector cells with interleukin-2 (IL-2). The phenotypic analysis of IL-2 cultures showed clearly the heterogeneity of lymphocyte subsets. The characterization studies demonstrated that CD56+, CD3- NK cells manifested most potent lysis of leukemia, CD56+, CD3+ T cells mediated some, but low, antileukemia activity and CD56-, CD3+ T lymphocytes were devoid of cytotoxicity.