Radioimmunoassay for antibodies to cytoplasmic ribosomes in human serum.

A radioimmunoassay for the detection of antibodies in human serum to tritium-labeled HeLa cell cytoplasmic ribosomes was developed with the use of Macaloid for the inhibition of endogenous ribonuclease activity. Antibodies were observed in the serum of patients with systemic lupus erythematosus in high incidence and titer. Patients with rheumatoid arthritis and chronic active hepatitis manifested a lower incidence and titer of antibodies to ribosomes, whereas serums from normal individuals and from patients with sarcoidosis, chronic glomerulonephritis, and malignant tumors showed no significant reactivity with cytoplasmic ribosomes. Maximum inhibition of the reaction was achieved with unlabeled HeLa cell ribosomes or rat liver ribosomes and partial inhibition by purified ribosomal RNA.