Autoantibodies to the Ro/SSA autoantigen are conformation dependent. II: Antibodies to the denatured form of 52 kD Ro/SSA are a cross reacting subset of antibodies to the native 60 kD Ro/SSA molecule

Autoimmunity. 1992;14(2):89-95. doi: 10.3109/08916939209083125.


The immune response to the Ro/SSA particles is conformation dependent. In sera with only anti-Ro/SSA precipitins, the autoantibodies to the 60 kD Ro/SSA are largely to the native 60 kD Ro/SSA while autoantibodies to the 52 kD Ro/SSA particle when present are exclusively to the denatured 52 kD Ro/SSA particle. Antibodies eluted from a recombinant 52 kD Ro/SSA fusion protein reacted in a sandwich ELISA which only measures antibody to native 60 kD Ro/SSA antigens and this reaction is largely inhibited by native homogeneous 60 kD Ro/SSA. In addition, antibody binding to the 52 kD Ro/SSA antigen in Western blot is also strongly inhibited by native 60 kD Ro/SSA. These experiment strongly suggest that reactivity of denatured 52 kD Ro/SSA antigen represents a cross reaction with autoantibodies directed to the native 60 kD Ro/SSA antigen. As a corollary of these experiments, data are presented that suggest the hY-RNAs are not associated with the 52 kD Ro/SSA protein but only with the 60 kD Ro/SSA protein. These data are consistent with the hypothesis that the autoanti-Ro/SSA response is driven by native 60 kD Ro/SSA and the immune response to denatured 52 kD Ro/SSA is largely a cross-reactive subset of the immune response to native 60 kD Ro/SSA.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antibody Specificity
  • Antigen-Antibody Reactions
  • Autoantibodies / immunology*
  • Autoantigens / immunology*
  • Cross Reactions
  • Humans
  • Nucleic Acid Conformation*
  • Nucleic Acid Denaturation
  • Protein Conformation*
  • Protein Denaturation
  • RNA, Small Cytoplasmic*
  • Recombinant Fusion Proteins / immunology
  • Ribonucleoproteins / immunology*


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