Detection and occurrence of the 60- and 52-kD Ro (SS-A) antigens and of autoantibodies against these proteins

Clin Exp Immunol. 1991 Oct;86(1):99-105. doi: 10.1111/j.1365-2249.1991.tb05780.x.


The simultaneous detection of anti-La, anti-60-kD Ro and anti-52-kD Ro antibodies by immunoblotting is greatly improved by changing the crosslinking level in the gel to an acrylamide/bisacrylamide ratio of 19:1. Using this method for the analysis of a number of systemic lupus erythematosus (SLE) and Sjögren's syndrome patient sera it was observed that antibody to the 52-kD Ro protein without anti-60-kD Ro antibody was restricted to Sjögren's syndrome patients (9/26), whereas antibody to the 60-kD Ro protein without contaminating anti-52-kD Ro antibody was only found in SLE patients (8/38). Moreover, in Sjögren's syndrome patient sera anti-Ro antibody was found only in combination with anti-La antibody (20/26), whereas in SLE patient sera anti-Ro antibody could be found without detectable anti-La specificity (4/38). Double immunofluorescence microscopy revealed that the 52-kD Ro and the 60-kD Ro proteins co-localize in the cytoplasm as well as in the nucleus, whereas immunoprecipitation of [32P]-labelled HeLa cell extract with monospecific anti-52-kD Ro and anti-60-kD Ro sera showed that both proteins are associated with the Ro RNAs. These data suggest the presence of both the 52-kD and the 60-kD Ro proteins in the same ribonucleoprotein complexes. To study the evolutionary conservation of the 52-kD Ro, the 60-kD Ro and the La proteins, extracts of cell lines derived from various mammalian species were analysed on Western blots using monospecific human antibodies. In contrast to the 60-kD Ro and the La antigens which are well conserved in evolution, the 52-kD Ro antigen could be detected in primate cells only by this immunological approach.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibody Specificity
  • Autoantibodies / analysis*
  • Autoantigens / analysis*
  • Autoimmune Diseases / immunology*
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • Molecular Weight
  • Nuclear Proteins / immunology
  • RNA, Small Cytoplasmic*
  • Ribonucleoproteins / immunology
  • Species Specificity
  • Tumor Cells, Cultured


  • Autoantibodies
  • Autoantigens
  • Nuclear Proteins
  • RNA, Small Cytoplasmic
  • RO60 protein, human
  • Ribonucleoproteins
  • SS-A antigen
  • SS-B antigen