Natural killer cell cytotoxicity and alpha-interferon in early rheumatoid arthritis

Natural killer (NK) cell number, cytotoxicity, and serum alpha-interferon (alpha-IFN) was measured in a group of early synovitis patients and compared to that of established rheumatoid arthritis patients and normal controls. No significant differences in NK cell number or serum alpha-IFN were found. NK cell cytotoxicity (NKCC) in the early synovitis group was significantly (p < 0.05) reduced compared to that of the normal controls and not significantly different from the established rheumatoid controls. There was a trend for those early synovitis patients with a good outcome to have higher NKCC. Low NKCC is evident very early in the course of rheumatoid arthritis and is thus unlikely to be secondary to chronic inflammation. There is no relationship between NKCC and alpha-IFN levels and the cause of the reduced NKCC is unknown. Alpha-IFN levels are not raised early in the course of RA.