Antibodies reacting with ribosomal ribonucleoprotein in connective tissue diseases

Abstract

Precipitating antibody to an antigen present in cytoplasm was detected in the sera of 7 patients with systemic lupus erythematosus, 1 patient with an overlap syndrome of systemic lupus erythematosus and rheumatoid arthritis, and 1 patient with mixed connective tissue disease. By physicochemical and enzymatic studies, the antigen was shown to have the properties of ribosomal ribonucleoprotein (r‐RNP). Cytoplasmic staining in immunofluorescence was observed with all the 9 sera containing antibodies to r‐RNP. In certain cases, cytoplasmic staining was associated with nucleolar staining. Antibody to r‐RNP is different in immunologic specificity and clinical significance from antibody to nuclear RNP and is present primarily in patients with systemic lupus erythematosus.