The activity of natural killer cells in patients with rheumatoid arthritis: I. The effect of drugs used in vivo.

The role of natural killer (NK) cells in vivo remains uncertain, but they have been implicated in a number of protective and aggressive host responses. We have found the NK activity of most patients with rheumatoid arthritis (RA) to be significantly depressed below the values for a control healthy population. This depression is not related to the use of myochrysine, methotrexate or penicillamine. Auranofin, which has a stimulatory effect in vitro, seemed in vivo to cause a further depression. ASA and indomethacin, when given to normal subjects, stimulated NK activity. The reduced NK activities seen in patients with RA taking these and other non-steroidal anti-inflammatory agents remains unexplained.