Spectrum of antinuclear and anti-cytoplasmic antibodies in dermatomyositis and polymyositis overlap syndromes

Antinuclear antibodies (ANA) of the IgG class were detected in 60% of patients with dermatomyositis. Only in 16% could we demonstrate precipitating antibodies against the nuclear Mi-2 antigen. These antibodies are considered to be serological markers of dermatomyositis. The ANA spectrum in polymyositis-overlap syndrome was considerably more heterogeneous: patients with polymyositis/progressive systemic scleroderma overlap had antibodies against the nucleolar PM-Scl antigen or the nuclear Ku antigen. Cytoplasmic antibodies to Jo-1 were present in polymyositis associated with Sj?gren's syndrome and pulmonary fibrosis. Antibodies against ribosomal ribonucleoprotein were found in polymyositis with systemic lupus erythematosus and antibodies to nuclear ribonucleoprotein in polymyositis associated with mixed connective tissue disease. The investigation demonstrates that the characterization of ANA specificities helps to differentiate between dermatomyositis and distinct forms of polymyositis-overlap syndrome.