Autoimmune (Type Ii) Reactions to Drugs

AUTOIMMUNE (TYPE II) REACTIONS TO DRUGS

Certain autoimmune syndromes can be induced by drugs. Examples include systemic lupus erythematosus following hydral-azine or procainamide therapy, “lupoid hepatitis” due to cathartic sensitivity, autoimmune hemolytic anemia resulting from methyl-dopa administration, thrombocytopenic purpura due to quini-dine, and agranulocytosis due to a variety of drugs. As indicated, a number of drugs are associated with type I and type II reactions. In these drug-induced autoim-mune states, IgG antibodies bind to drug-modified tissue and are destroyed by the complement system or by phagocytic cells with Fc receptors. Fortunately, autoimmune reactions to drugs usually subside within several months after the offending drug is with-drawn. Immunosuppressive therapy is warranted only when the autoimmune response is unusually severe.