Molecular characterization of ribonucleoprotein antigens bound by antinuclear antibodies. A diagnostic evaluation

The specificity of antinuclear antibodies in sera from 54 patients with various rheumatic diseases was analyzed by immunoprecipitation of 32P- or 35S-methionine-labeled HeLa cell extracts. Of 35 sera giving a speckled and/or homogeneous immunofluorescence pattern in rat liver nuclei, 20 contained antibodies to nuclear ribonucleoproteins, which are defined by their ribonucleic acid and protein components. Four sera reacted with a nuclear antigen (Ga) which has not been described so far. Of 19 sera with antinucleolar antibodies, 18 did not react with nuclear or nucleolar ribonucleoproteins. Correlation of these molecularly defined antinuclear antibody specificities with immunofluorescence patterns and rheumatic diseases is discussed.