Antibodies to components of extractable nuclear antigen. Clinical characteristics of patients.

Forty-four patients with antibodies to ribonuclease-sensitive extractable nuclear antigen (ENA), ribonuclease-resistant ENA, or both, are described. Most patients with antiribonucleoprotein (anti-RNP) antibodies have overlapping features of systemic lupus erythematosus (SLE), progressive systemic sclerosis (PSS), and polymyositis, and have a low incidence of nephritis. Most patients with antibody solely to ribonuclease-insensitive ENA have SLE; these patients with SLE are typical of the general SLE population, except that they demonstrate an increased incidence of Raynaud phenomenon. Furthermore, it is shown that antibody to ENA may occur in other rheumatic and nonrheumatic diseases, and that not all patients who have a clinical overlap of SLE and PSS that is suggestive of mixed connective tissue disease have anti-RNP antibody.