What type of antibodies would suggest a diagnosis of drug-induced systemic lupus erythematosus?

Drug-induced systemic lupus erythematosus (SLE) is commonly associated with the presence of antihistone antibodies. These antibodies are specific for drug-induced forms of lupus, particularly in the context of certain medications such as procainamide, hydralazine, and isoniazid.

Antihistone antibodies are indicative of the presence of autoantibodies that react against histones, which are proteins around which DNA is wound. In drug-induced SLE, the administration of certain drugs leads to the modification of histones, which can subsequently trigger an autoimmune response and the formation of these specific antibodies.

While antinuclear antibodies (ANA) can be found in various forms of lupus and other autoimmune disorders, including drug-induced lupus, their presence alone is not specific to drug-induced SLE. Rheumatoid factor is associated primarily with rheumatoid arthritis and not typically involved in lupus. Anti-topoisomerase antibodies are more specific for systemic sclerosis (scleroderma) rather than lupus. Therefore, the presence of antihistone antibodies serves as a crucial marker in suggesting a diagnosis of drug-induced systemic lupus erythematosus.