SCREENING FOR AUTOANTIBODIES TO THE NUCLEOLAR U3-RIBONUCLEOPROTEINS AND TH(7-2)-RIBONUCLEOPROTEINS IN PATIENTS SERA USING ANTISENSE RIBOPROBES

In this study we report the detection of autoantibodies to the nucleol ar U3- and Th(7-2) ribonucleoprotein (RNP) particles in sera from pati ents with connective tissue diseases. The method described employs rad ioactively labelled antisense U3- and Th RNA which are hybridized to i mmunoprecipitated U3- or Th RNA from a HeLa cell extract. Of the 66 se ra that were screened with this method seven sera (11%) precipitated o nly Th RNP, 16 sera (24%) precipitated only U3 RNP and 4 sera (6%) pre cipitated both U3- and Th RNP. Both anti-U3 RNP and anti-Th RNP activi ty appeared to be mostly associated with scleroderma or scleroderma-as sociated diseases. Using this method we also showed that some of the T h RNP particles in a cell extract are associated with the La autoantig en. We conclude that for the identification of immunoprecipitated RNAs this method is very sensitive and provides unambiguous data.