Generation of NK cell activity from human bone marrow.

This study was designed to examine the effect of interleukin 2 (IL 2) on cytotoxic activity of human bone marrow cells and to characterize the IL 2-dependent killer cells and the cell population required for their induction. We have demonstrated that the most aggressive IL 2-dependent killer cells (directed against leukemic and solid cancer targets) exhibited LGL morphology and expressed NK cell-associated antigens NKH1 and CD16, but not T cell-associated antigens CD3, CD4, CD5, or CD8. Similarly, the bone marrow cell population necessary for induction of killer cells with highest cytotoxic activity displayed NK cell surface characteristics, as exemplified by CD16 and Leu-7 antigens. On the contrary, very low or no lytic activity was generated from the bone marrow cell population expressing T cell markers CD3 and CD5. These data indicate that the IL 2-dependent bone marrow-derived killer cells with antitumor activity were activated NK cells. If T cells are involved at all in IL 2-dependent bone marrow killing, their potency is inferior to that of activated NK cells. The clinical applications of these studies are discussed.