BONE-MARROW AND PERIPHERAL-BLOOD NATURAL-KILLER-CELL ACTIVITY IN LYMPHOMAS - ITS RESPONSE TO IL-2

Natural killer (NK) cytotoxic activity was simultaneously investigated in bone marrow mononuclear cells (BMMC) and peripheral blood lymphocy tes (PBL) from nine Hodgkin's disease (HD) and 15 non-Hodgkin lymphoma (NHL) untreated patients. Twenty-five PBL samples and seven bone marr ow specimens from healthy individuals were also included as control gr oup (C). NK cell activity was evaluated in basal condition and post-st imulation with human recombinant IL-2 (rIL-2). Data were expressed in K values (number of BMMC or PBL needed to lyse 50% of the target cells ). In basal condition, both HD and NHL patients showed a NK cell activ ity comparable to the C group, both in BMMC (HD, K = 2.48 +/- 1.3; NHL , K = 3.8 +/- 2.0; C, K = 3.2 +/- 0.7) and PBL (HD, K = 2.0 +/- 1.0; N HL, K = 2.3 +/- 1.0; C, K = 2.2 +/- 0.2). Stimulation with rIL-2 induc ed a significant and comparable enhancement of the NK activity in PBL from HD, NHL and C while the response to rIL-2 of the BMMC in most of the HD and NHL patients was significantly greater than the C group. Re sponder cells were characterized by negative selection with specific M oAb plus complement as a CD3-, CD16+, CD56+ cytotoxic cell and further confirmed by flow cytometry. We postulate that IL-2 activation of bon e marrow NK cell precursors, in addition to enhancing the activity of circulating NK, may be of value for the therapeutic rationale of IL-2 in patients with lymphoma.