Help to diagnose drug-induced lupus (DIL) and systemic lupus erythematosus (SLE). Antibodies to both chromatin and histones have been found in patients with procainamide-induced lupus; however, patients with lupus induced by drugs such as quinidine, penicillamine, methyldopa, and acebutolol have antibodies to chromatin but not antihistone. Antichromatin antibodies are found in 50% to 90% of SLE patients and have been linked with proteinuria in SLE patients.