Analysis of autoimmune sera by immunoprecipitation of cellular RNPs

Abstract

Rheumatic diseases are often accompanied by autoimmune antibodies directed towards cellular proteins. Many of these autoantigens are protein components of cytoplasmic and nuclear ribonucleoprotein (RNP) particles (reviewed in [1]). Patients with systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD) and Sjögren’s syndrome often develop antibodies against the snRNP, Ro and La ribonucleoprotein particles, respectively (Table 1). Other RNP particles are recognized with lower frequency [2]. The close correlation of these antibody activities with a disease makes them valuable diagnostic markers. The RNA components of the particles are of unique low molecular weight and often abundant, making them easy to identify (Table 2). Therefore the immunoprecipitation of cellular RNPs with autoimmune sera and analysis of their RNA components is a sensitive assay for autoimmune activities which tests the ability of antibodies to recognize native antigens with high affinity [3–5].