Drug effects on autoantibodies and immune complexes.

In connective tissue diseases, putatively immunosuppressive drugs may lower antinuclear antibody (ANA), anti-DNA antibody and rheumatoid factor titres. Penicillamine may induce or increase titres of antinuclear and/or anti-muscle antibodies. The mechanism of induction of penicillamine antinuclear autoimmunity evidently differs from that seen with hydrallazine and procainamide. While the latter may induce circulating immune complex formation, the effect of penicillamine on circulating immune complex levels in rheumatoid arthritis is variable. Our recent findings will be discussed.