Immunological studies in patients with rheumatoid arthritis receiving azathioprine and myocrisin in combination.

Thirty-one patients with classical or definite rheumatoid arthritis (RA), on treatment with azathioprine and sodium aurothiomalate in combination were studied. Absolute lymphocyte counts and IgA levels were reduced but this did not reach statistical significance. Lymphocyte transformation with phytohaemagglutinin (PHA) showed no significant difference from a control group. However, antibody dependent cell-mediated cytotoxicity was significantly impaired compared to rheumatoid controls (p less than 0.001). There was no relation to the degree of impairment of ADCC and the current dose of azathioprine nor to the total dose or duration of therapy. Inhibiting material to cell-mediated cytotoxicity was present in the sera of 23 patients but its presence showed no relation to the degree of cytotoxicity exhibited by cells in the same patient. Our studies of cellular cytotoxicity have revealed alterations in cellular function possibly attributable to azathioprine.