Characterization of the Su antigen, a macromolecular complex of 100/102 and 200-kDa proteins recognized by autoantibodies in systemic rheumatic diseases

Clin Immunol Immunopathol. 1994 Oct;73(1):132-41. doi: 10.1006/clin.1994.1179.


The Su autoantigen was characterized biochemically using human and murine autoimmune sera and the clinical significance of anti-Su antibodies was studied in 236 Japanese and 160 American patients with systemic rheumatic diseases. Anti-Su in immunodiffusion (ID) was strongly associated with immunoprecipitation of one or more 100- to 102-kDa proteins by MRL/lpr mouse sera (27/32 of ID positive vs 4/20 of ID negative, P = 0.000016), and all four human anti-Su reference sera immunoprecipitated the 100/102-kDa protein(s). In addition, all sera immunoprecipitated a less efficiently labeled approximately 200-kDa protein that comigrated on sucrose density gradients with the 100/102-kDa proteins. Based on these data, a complex of the 100/102-kDa and 200-kDa proteins is likely to be the main target of anti-Su antibodies. Three of four anti-Su monospecific sera were negative for immunofluorescent antinuclear antibodies (ANA), suggesting anti-Su antibodies may be associated with a negative ANA in some cases. Autoantibodies to Su were detected frequently by immunoprecipitation in systemic lupus erythematosus (17-21%), scleroderma (13-20%), and overlap syndrome (22-40%) and were associated with autoantibodies to Ku.

Publication types

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

MeSH terms

  • Animals
  • Antigen-Antibody Reactions
  • Autoantibodies / immunology
  • Autoantigens / chemistry*
  • Centrifugation, Density Gradient
  • Fluorescent Antibody Technique
  • Humans
  • Immunoblotting
  • Immunodiffusion
  • Mice
  • Nuclear Proteins / chemistry
  • Precipitin Tests
  • Proteins / chemistry*
  • Proteins / immunology
  • Rheumatic Diseases / immunology*
  • Sucrose


  • Autoantibodies
  • Autoantigens
  • Nuclear Proteins
  • Proteins
  • Su autoantigen
  • Sucrose