Molecular properties of the Ro/SSA antigen and enzyme-linked immunosorbent assay for quantitation of antibody.

H Yamagata; J B Harley; M Reichlin

doi:10.1172/JCI111460

Published August 1, 1984 - More info

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Abstract

Antibodies to the Ro/SSA antigen occur in patients with systemic lupus erythematosus and Sjögren's syndrome. An immunoaffinity method for the preparation of electrophoretically homogeneous Ro/SSA antigen is described. Several molecular properties of the antigen have been determined. The native RNA protein particle has a molecular weight of approximately 100,000 D determined by gel filtration. Sodium dodecyl sulfate-analysis of the purified Ro/SSA antigen and analysis by staining of bands with silver and Coomassie Blue, Western blotting, and RNAase treatment leads to a hypothesis for the structure of the particle in which an antigenic 60,000 protein is bound to 24,000-27,000 RNA molecules which are not antigenic. An enzyme-linked immunoabsorbent assay method for assay of anti-Ro/SSA is also described which sensitively measures antigen binding at dilutions of sera containing anti-Ro/SSA precipitins up to 10(7) fold. Normal sera on average have 10(3) less binding activity.

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