IgM and IgG subclass distribution of human anti-Ro/SSA 60 kDa autoantibodies

Scand J Immunol. 1994 Feb;39(2):179-83. doi: 10.1111/j.1365-3083.1994.tb03357.x.


The Ro/SSA and La/SSB antigens are common targets for autoantibodies found in the sera of patients with Sjögren's syndrome and SLE. The anti-Ro/SSA and anti-La/SSB antibodies often appear together but are not cross-reactive. This paper describes the humoral autoimmune response to the Ro/SSA 60 kDa protein moiety with respect to the presence of IgM and IgG1-4 antibodies. IgM antibodies to the Ro 60 kDa protein coexisted with IgG anti-Ro 60 kDa antibodies in nearly half of the sera. A similar fraction also contained IgM anti-La/SSB antibodies. The frequency of sera with IgM antibodies of both specificities was that expected from random overlap. A predominating IgG1 anti-Ro 60 kDa response was found in all patients, but anti-Ro 60 kDa antibodies of the other IgG subclasses were present also in a high number of sera. This is in contrast to the reported IgG subclass distribution of anti-La/SSB antibodies. Mapping of IgM and IgG1-4 antibody recognition of different parts of the Ro 60 kDa protein was also performed. IgM and IgG1-4 antibodies of all sera reacted with the central part of the Ro 60 kDa protein, encompassing amino acid residues 181-320.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autoantibodies / blood*
  • Autoantigens / immunology*
  • Humans
  • Immunoblotting
  • Immunoglobulin G / blood*
  • Immunoglobulin M / blood*
  • RNA, Small Cytoplasmic*
  • Rheumatic Diseases / immunology*
  • Ribonucleoproteins / immunology*


  • Autoantibodies
  • Autoantigens
  • Immunoglobulin G
  • Immunoglobulin M
  • RNA, Small Cytoplasmic
  • Ribonucleoproteins
  • SS-A antigen
  • SS-B antigen
  • TROVE2 protein, human