Immunoreactivity to nuclear antigens in systemic lupus erythematosus with or without nephritis, and in other connective tissue diseases, with particular reference to the RNA-protein antigen.

The incidence of autoantibodies to various nuclear antigens was studied in 64 patients with systemic lupus erythematosus (SLE), 137 patients with various connective tissue diseases, 63 other patients and 90 controls. A positive correlation was found between SLE, nephritis and the presence of antibody against native DNA. Antibody to denatured DNA showed no specificity for SLE and was correlated with the absence of nephritis. Antibody to RNA protein occurred mainly in SLE, regardless of the presence or absence of nephritis.