Modulation of natural killer activity by aspirin: I. In vitro effect of aspirin.

It has been previously shown that the Natural Killer (NK) cell activity of peripheral blood mononuclear cells (NMC) from healthy donors can be augmented by in vitro coculture of MNC with melanoma cells. This augmentation was not seen when the blood donors had taken acetylsalicylic acid (ASA) 12 h before venipuncture. To examine the direct action of ASA on the NK cell activity we treated MNC in vitro by ASA and tested the cytotoxic activity on NK-sensitive target cells. Neither the spontaneous NK cell activity nor the in vitro stimulation of NK cell activity by beta-interferon (IFN) was influenced by ASA treatment in vitro.