Detection by ELISA of antibodies to small RNA protein particles in systemic lupus erythematosus patients whose sera lack precipitins.
Three hundred five consecutive patients with systemic lupus erythematosus (SLE) have been evaluated for antibodies to the RNA protein particles, Sm, nRNP, Ro/SSA, and La/SSB. Precipitating antibodies were found in 224 (73.1%). With the use of ELISA methodology with affinity-purified antigens, 76 sera from precipitin-negative patients were assayed and 35 had elevated levels of one or more of the autoantibodies. Of these, 27 (36%) had elevated anti-nRNP and 17 (22%) had elevated anti-Ro/SSA. Six of the seven patients with anti-La/SSB (18%) also had anti-Ro/SSA paralleling the close association of these two antibodies noted by precipitin analysis in which 38 of 39 patients with anti-La/SSB precipitins also have anti-Ro/SSA precipitins. Thus, 258 of the 305 SLE sera (84.6%) have elevated anti-RNA protein levels. This represents a minimum estimate of the frequency of these antibodies since longitudinal study of individual patients shows that anti-RNA protein levels may vary from normal to 1000 times over background at different times. Quantitative studies over time in two patients with both anti-Sm and anti-nRNP show that anti-nRNP increased 10- to 100-fold while anti-Sm changed little. These quantitative changes may relate to clinical phenomena.
D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000302:isolation & purification*; D001324:Autoantigens / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008181:Lupus Nephritis / Q000276:immunology; D008297:Male; D011234:Precipitins / Q000302:isolation & purification; D012261:Ribonucleoproteins / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
D000974:Antibodies, Antinuclear; D001324:Autoantigens; D011234:Precipitins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; C035356:SS-A antibodies; C035357:SS-B antibodies; D055517:snRNP Core Proteins