[Effect of interferon-alpha (MOR-22) on human NK cell activity].

We studied the effect of human lymphoblastoid interferon (IFN-alpha; MOR-22) on the natural killer (NK) cell activity of human peripheral blood lymphocytes (PBL). The NK cell activity of PBL from 12 healthy donors against K562 target cells was augmented by an average of 3.8 times by pretreatment with IFN 1,000 IU/ml for 2h. Augmentation was observed after pretreatment with IFN at a concentration of 10 IU/ml for 2 h or 1,000 IU/ml for 30 min. Augmented NK cell activity brought about by pretreatment with IFN showed a wide cytotoxic spectrum against human tumor cell lines. The sensitivities of the cell lines to NK cell activity were independent of the cell origin or antiproliferative effect of IFN. It was suggested that the NK cells activated by IFN might be a population expressing the Leu-11 positive marker because of nearly complete depletion of NK activity by pretreatment with anti-Leu-11b and complement. These results suggest that the activation of NK cells by IFN may play an important role in the antitumor effect of IFN.