Studies on drug-induced lupus erythematosus in mice. II. Drug-induced smooth muscle and skeletal muscle antibodies.

Hydralazin, isoniazid, procainamide, α-methyldopa and chlorthalidone were given orally to mice of three inbred strains: C57/B1/6J, BALB/cJ and A/Jax. It was found that α-methyldopa and chlorthalidone induced smooth muscle (SMA) and skeletal muscle (SKMA) antibodies in all three strains. Hydralazin appeared to induce smooth muscle antibodies in A/Jax mice, but not in the other two strains. The smooth muscle antibodies correlated with one subtype of skeletal muscle antibodies. Lymphocellular infiltrates were found in the livers of a number of SMA-positive animals. No differences were noted between males and females. It is suggested that some drugs can induce changes in liver membrane antigen, resulting in an autoimmune response with formation of SMA and lymphocellular infiltration.