D-penicillamine treatment in rheumatoid arthritis monitored by plasma alfa-1-antitrypsin-IgA complexes and plasma and urinary sulphur containing aminoacids.

D-Penicillamine treatment in rheumatoid arthritis resulted in a fall in plasma alfa-1-antitrypsin-IgA complexes which was significantly more pronounced among responders than among non-responders. Plasma free cystine levels also fell during D-penicillamine treatment, the fall being dose dependent up to a daily dose of 500 mg. Higher doses did not result in further lowering, and no difference was detected between responders and non responders. The dominating sulphur containing aminoacid excreted in the urine was penicillamine-cysteine disulphide, the concentration of which did not correlate to either toxicity or clinical effectiveness, but showed much individual variation. The slow kinetics of change in the complex concentration taken together with in vitro experiments, suggest that the effect of D-penicillamine is more likely to be on the de novo formation of the complexes, rather than on their reduction.