Serological tests detect autoantibodies directed against histone proteins, the essential proteins around which DNA wraps to form nucleosomes in the cell nucleus. These antibodies are commonly associated with drug-induced lupus erythematosus (DIL), appearing in more than 95% of cases. They may also be found in a smaller percentage of patients with primary systemic lupus erythematosus (SLE) (30–80%), but are usually accompanied by other antibodies such as anti-dsDNA.