Antibodies to synovial antigens in recent-onset rheumatoid arthritis.
OBJECTIVE
To identify synovial antigens that bind to serum antibodies from subjects with recent-onset rheumatoid arthritis (RA) (< 6 months of synovitis).


METHODS
Soluble and insoluble fractions of Triton X-100 extracts of RA and normal synovial tissue, and normal spleen and placenta, were immunoblotted with sera from 27 patients with recent-onset RA, 13 autoimmune disease control subjects, and 13 blood bank control donors. Bound immunoglobulin was probed with 125I-labeled protein A.


RESULTS
Antibodies in the sera of 20 (74%) patients with recent-onset RA recognized at least 1 of 5 antigens in both a disease- and tissue-specific and nonspecific manner. Anti-La antibodies, usually associated with primary Sjögren's syndrome, were detected in 2 sera. Eight sera had increased reactivity to an IgG heavy and light chain dimer. There was strong binding of 8 sera with a 35-kd doublet and of 3 sera with a 55-kd species in RA and normal synovial lysates (insoluble fractions). Two sera uniquely recognized a 45-kd protein only in the RA synovial lysate (soluble fraction).


CONCLUSIONS
IgG antibodies in the sera of patients with recent-onset RA show positive immunoblots for 3 novel synovial antigens of 35-kd, 55-kd, and 45-kd, as well as for 2 previously characterized antigens (La and IgG). Thus, a variety of synovial antigens appear to be recognized by B cells even early in the clinical course of RA.
McColl
G J
GJ
Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.
Cram
D S
DS
Harrison
L C
LC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000906:Antibodies / Q000276:immunology* / Q000378:metabolism; D000918:Antibody Specificity; D000941:Antigens / Q000302:isolation & purification*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001324:Autoantigens / Q000032:analysis / Q000276:immunology; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012261:Ribonucleoproteins / Q000032:analysis / Q000276:immunology; D013583:Synovial Membrane / Q000276:immunology*; D013997:Time Factors; D000097585:SS-B Antigen
D000906:Antibodies; D000941:Antigens; D001324:Autoantigens; D007074:Immunoglobulin G; D012261:Ribonucleoproteins; D000097585:SS-B Antigen