Characterization of the Su antigen, a macromolecular complex of 100/102 and 200-kDa proteins recognized by autoantibodies in systemic rheumatic diseases.
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.
Satoh
M
M
Department of Medicine, Thurston Arthritis Research Center, Chapel Hill, North Carolina.
Langdon
J J
JJ
Chou
C H
CH
McCauliffe
D P
DP
Treadwell
E L
EL
Ogasawara
T
T
Hirakata
M
M
Suwa
A
A
Cohen
P L
PL
Eisenberg
R A
RA
D000818:Animals; D000937:Antigen-Antibody Reactions; D001323:Autoantibodies / Q000276:immunology; D001324:Autoantigens / Q000737:chemistry*; D002499:Centrifugation, Density Gradient; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D005779:Immunodiffusion; D051379:Mice; D009687:Nuclear Proteins / Q000737:chemistry; D011233:Precipitin Tests; D011506:Proteins / Q000737:chemistry* / Q000276:immunology; D012216:Rheumatic Diseases / Q000276:immunology*; D013395:Sucrose
D001323:Autoantibodies; D001324:Autoantigens; D009687:Nuclear Proteins; D011506:Proteins; C089635:Su autoantigen; D013395:Sucrose