AUTOLOGOUS ENHANCEMENT BY INTERFERON OF NATURAL-KILLER ACTIVITY OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES

THE in vitro action of interferon (IFN)-alpha and IFN-gamma from six h ealthy donors and ten patients with multiple sclerosis (MS) on natural killer (NK) activity of peripheral blood lymphocytes (PBL) was studie d in an autologous system. The NK activity of PBL was detected by a cy totoxic test using H-3-uridine human erythromyeloblast K562 cells. Aut ologous IFN-ol and IFN-gamma did not augment NK activity of PBL from h ealthy donors in vitro, whereas in samples from MS patients the IFNs s trongly stimulated NK cell cytotoxic function. This stimulation sugges ts the existence of an inhibitor of regulatory IFN action, that is pro duced in healthy donors simultaneously with IFN in response to IFN ind uction, but which is lacking in commercial IFN preparations. The facto r-containing supernatants from healthy donors reduced the stimulatory action of autologous IFNs in patients with MS almost until complete bl ockade. Because this inhibitor was absent in patients with MS, deficie ncy of an inhibitor of IFN regulatory action in MS could open the way to treatment of this compartment of the immune system.