[Detection of autoantibodies to extractable nuclear antigens in autoimmune diseases of rheumatic origin using immunoblotting--comparison with counter-electrophoresis].

Sera from 82 patients with rheumatic autoimmune disease were tested for anti-ENA antibodies by immunoblotting and counterimmunoelectrophoresis (CIE), using HeLa cell extract and rabbit thymus extract, respectively, as antigens. Anti-ENA antibodies were more frequently detected and could be better differentiated by immunoblotting rather than by CIE. There was especially an increase in anti-Sm antibodies (23, in contrast to four positive results), which was only detectable in serum samples for the 59 SLE patients. The sera of the six patients with MCTD all reacted with the 68 U1-RNP antigen. The sera of the five patients with Sjögren's syndrome only recognized the 50k La antigen, while other anti-ENA antibodies were not observed. In SLE anti-La antibodies were often associated with other anti-ENA antibodies. Seven out of eight SLE patients showing a combined detection of antibodies against Sm, U1-RNP and La by immunoblotting demonstrated severe organ involvements, especially lupus nephritis. Therefore, the characterization of anti-ENA antibodies by immunoblotting may contribute to improve the differentiation of connective tissue diseases.