Frequent induction of insulin autoantibodies by D-penicillamine in patients with rheumatoid arthritis.

D-Penicillamine is a drug known to induce various immunological abnormalities. We used a competitive radiobinding assay, to evaluate the presence of insulin autoantibodies in 42 patients with rheumatoid arthritis (RA), under various treatment modalities. In 11/42 (26.2%) patients, the levels of insulin autoantibodies (range 59-1970 nU/ml) exceeded our upper limit of normal range (50 nU/ml). Nine of these 11 (81.8%) insulin autoantibodies positive patients had been treated with D-penicillamine. Out of 21 D-penicillamine treated patients, 9 (42.9%) were insulin autoantibodies positive (range 80 to 1970 nU/ml). An inverse correlation was found between the concentration of insulin autoantibodies and the time interval since the last drug administration, R = -0.58 (p < 0.05). No correlation was found between the autoantibodies levels and age, or duration of D-penicillamine treatment. In summary, elevated concentration of serum insulin autoantibodies are most probably induced by D-penicillamine therapy in patients with RA and tend to decrease after the drug withdrawal.