Antibodies against extractable nuclear antigens (ENA) in systemic scleroderma.

Antibodies against nuclear ribonucleoprotein (RNP) were found in 5 of 63 cases of systemic scleroderma, whereas they were present in all but one case of mixed connective tissue disease and in 15 of 67 cases of systemic lupus erythematosus. In all RNP positive cases of systemic scleroderma there were some features of other collagen diseases, and their course was relatively more benign. Studies of RNP antibodies in systemic scleroderma may be of importance for treatment and prognosis.