THE EFFECT OF RECOMBINANT GRANULOCYTE MACROPHAGE-COLONY-STIMULATING FACTOR AND RECOMBINANT GRANULOCYTE-STIMULATING FACTOR IN COMBINATION WITH INTERLEUKIN-2 ON IN-VITRO NATURAL-KILLER-CELL ACTIVITY

Interleukin-2 (IL-2) has been demonstrated to stimulate natural killer (NK) cells to kill autologous leukemic cells. However, IL-2 has sever al potentially harmful dose-limiting side effects. Because recombinant granulocyte/monocyte colony stimulating factor (rGM-CSF) was reported to have a potential antileukemic effect in experimental animals, we h ave tested the potential enhancing effect of rGM-CSF and rG-CSF on NK activity, in vitro, in healthy human donors. We have also examined the possibility of augmenting the IL-2 effect on NK cells by either rGM-C SF or rG-CSF. To determine if either rGM-CSF or rG-CSF can augment NK cell activity, we incubated normal peripheral blood mononuclear cells (PBMC) from 10 normal adult volunteers with G-CSF or GM-CSF for 3 days and then tested them for NK cell activity. We found that NK activity (as detected by lysis of K562 target cells in a 3-hour Cr-51-release a ssay) was not affected by varying doses of rGM-CSF (10, 50, 100, 500 n g/10(6) cells) or rG-CSF (10, 100, 500 units/10(6) cells). Moreover, t hese cytokines did not enhance the effect of a suboptimal dose (5 unit s/10(6) cells) of rIL-2 in augmenting NK activity.