To detect the antibodies against human fibrinogen (FIB) β67-77 peptide and citrullinated human FIB β67-77 peptide in rheumatoid arthritis (RA) and examine their diagnostic values in RA.
The antibodies against FIB β67-77 peptide and citrullinated FIB β67-77 peptide were detected by enzyme-linked immunosorbent assay (ELISA) in 227 RA patients, 188 other connective tissue disease and 100 healthy controls. And their clinical applications were analyzed in the diagnosis of RA.
(1) The prevalence and titer of IgG, IgA and IgM isotypes of anti-citrullinated FIB β67-77 peptide antibodies in RA were significantly higher than those with other rheumatic diseases and healthy individuals. However, the prevalence of anti-FIB β67-77 peptide antibodies in RA patients was similar to those with other rheumatic diseases and healthy individuals (P > 0.05). (2) The diagnostic sensitivity of IgG, IgA and IgM of anti-FIB β67-77 peptide antibodies for RA were 50.7%, 48.5% and 55.1% and the specificity 94.8%, 92.7% and 92.4% respectively. The sensitivity of combined detection of 3 subtypes was up to 87.7% and the specificity 78.5%. (3) No significant correlations existed between anti-citrullinated FIB β67-77 peptide antibodies, RF, anti-CCP antibody, AKA and APF respectively. Moreover, the seropositive rates of IgG, IgM and IgA of anti-citrullinated FIB β67-77 peptide were 52.9%, 39.2% and 54.9% in IgM-RF negative patients Versus 48.5%, 53.1% and 37.5% in anti-CCP antibody, AKA and APF negative patients respectively.
IgG, IgM and IgA antibodies to citrullinated FIB β67-77 peptide are sensitive and specific in the diagnosis of RA. And the test of anti-citrullinated FIB β67-77 peptide antibodies is especially useful in diagnosing RA with other negative autoantibodies.