Objective: 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.
Methods: 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.
Results: (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.
Conclusion: 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.