Studies on the Specificity and Clinical Correlation of Antiribosomal Antibodies in Systemic Lupus Erythematosus Sera

The specificity of antibodies reactive with cytoplasmic ribosomes detected in systemic lupus erythematosus (SLE) sera was studied by a radioimmunoassay procedure with 3H labeled HeLa cell polysomes. The antibodies were directed primarily against RNA or a ribosomal RNA-protein complex (rRNP). Anti-RNA antibodies exhibited comparable reactivity with ribosomal RNA, nuclear RNA, structural RNA, and a slightly lower degree of reactivity with low molecular weight RNA. Anti-rRNP antibodies may be detected by precipitation in agar gel and appear to require both the RNA and protein moieties of ribosomes for reactivity. SLE sera containing only anti-rRNP antibodies are limited to patients with active disease. Sera from patients with both active and inactive SLE contain either anti-RNA or a mixture of anti-RNA and anti-rRNP antibodies. The possible participation of anti-ribosomal antibodies in immune complex formation is discussed.