Clinical significance of screening for antibody to ribonucleoprotein.

Of more than 1500 sera screened for antinuclear antibody 13 were positive for antiribonucleoprotein (RNP). Nine patients had either systemic lupus erythematosus or mixed connective tissue disease. Four other had no significant medical problems. The detection of anti-RNP antibody does not have diagnostic specificity and may not indicate active collagen disease.