Restoration of impaired natural killer cell activity of B-chronic lymphocytic leukemia patients by recombinant interleukin-2.

Natural killer (NK) function in the majority of B-cell chronic lymphocytic leukemia patients is markedly deficient. This study was undertaken to determine if the biological response modifier interleukin-2 (IL-2), which is a potent augmenter of normal individuals' NK activity, could augment the low NK activity in these patients. Peripheral blood lymphocytes (PBL), depleted of B-cells, from most B-CLL patients exhibited low natural killer activity against NK-sensitive K562 cells and against herpes simplex virus (HSV)-infected lymphoblastoid cell lines (LCL). Incubation of patients' B-cell-depleted PBL with recombinant IL-2 resulted in augmentation of their NK activity against both K562 cells and HSV-infected cells. Furthermore, whereas large granular lymphocytes (LGL) isolated from CLL patients are deficient in cytoplasmic granules, which are thought to play a role in NK-cell-mediated lysis, treatment of patients' LGL resulted in increased granulation by 4 hr after treatment with IL-2 and showed a concomitant increase in lytic activity comparable to that of normal individuals.