OBJECTIVE: To identify immunodominant epitopes in natural filaggrin that are reactive with antifilaggrin autoantibodies (AFA) in the sera of patients with rheumatoid arthritis (RA) and to explore their use in a diagnostic assay format. METHODS: Based on the results of epitope mapping of human natural filaggrin as well as molecular modeling and computational chemistry, synthetic peptides together with recombinant citrullinated filaggrin were evaluated by a line immunoassay (LIA) for AFA detection. Diagnostic performance was assessed using 336 RA and 253 disease control sera and was compared with that of reference methods. RESULTS: Several immunoreactive epitopes were identified in natural filaggrin, all of which contained at least 1 citrulline residue. Three antigenic substrates, including 2 synthetic peptides and recombinant citrullinated filaggrin showing maximal reactivity on LIA, were finally selected. Using the 3-antigen LIA3, overall sensitivity, specificity, and positive predictive value for RA were 65.2%, 98.0%, and 89.1%, respectively, compared with 61.9%, 98.8%, and 92.8% using the 2-antigen LIA2 (without recombinant protein). Thirty-seven percent of the rheumatoid factor (RF)-negative RA samples (30 of 81) were AFA-positive by LIA2, and 52 of 54 RF-positive control samples had no AFA detected on LIA2. Higher specificity and sensitivity were obtained by LIA2 versus anti-RA33 immunoblot, whereas good agreement was observed with antikeratin antibody testing. LIA performed significantly better than AFA immunoblotting using natural filaggrin, at a specificity level of 99% (P = 0.0047). CONCLUSION: Citrullinated residues are present in immunoreactive epitopes of natural human filaggrin. AFA can be readily detected by citrullinated peptides in an LIA-based test, resulting in high specificity and positive predictive value for RA. The LIA could serve as a user-friendly alternative to existing immunofluorescence tests and AFA immunoblot techniques. Given its complementarity to RF, this test can be a valuable tool in the differential diagnosis of arthritis.
OBJECTIVE: To identify immunodominant epitopes in natural filaggrin that are reactive with antifilaggrin autoantibodies (AFA) in the sera of patients with rheumatoid arthritis (RA) and to explore their use in a diagnostic assay format. METHODS: Based on the results of epitope mapping of human natural filaggrin as well as molecular modeling and computational chemistry, synthetic peptides together with recombinant citrullinated filaggrin were evaluated by a line immunoassay (LIA) for AFA detection. Diagnostic performance was assessed using 336 RA and 253 disease control sera and was compared with that of reference methods. RESULTS: Several immunoreactive epitopes were identified in natural filaggrin, all of which contained at least 1 citrulline residue. Three antigenic substrates, including 2 synthetic peptides and recombinant citrullinated filaggrin showing maximal reactivity on LIA, were finally selected. Using the 3-antigen LIA3, overall sensitivity, specificity, and positive predictive value for RA were 65.2%, 98.0%, and 89.1%, respectively, compared with 61.9%, 98.8%, and 92.8% using the 2-antigen LIA2 (without recombinant protein). Thirty-seven percent of the rheumatoid factor (RF)-negative RA samples (30 of 81) were AFA-positive by LIA2, and 52 of 54 RF-positive control samples had no AFA detected on LIA2. Higher specificity and sensitivity were obtained by LIA2 versus anti-RA33 immunoblot, whereas good agreement was observed with antikeratin antibody testing. LIA performed significantly better than AFA immunoblotting using natural filaggrin, at a specificity level of 99% (P = 0.0047). CONCLUSION: Citrullinated residues are present in immunoreactive epitopes of natural human filaggrin. AFA can be readily detected by citrullinated peptides in an LIA-based test, resulting in high specificity and positive predictive value for RA. The LIA could serve as a user-friendly alternative to existing immunofluorescence tests and AFA immunoblot techniques. Given its complementarity to RF, this test can be a valuable tool in the differential diagnosis of arthritis.
Authors: Bert Vander Cruyssen; Ilse E A Hoffman; Isabelle Peene; Ann Union; Herman Mielants; Lydie Meheus; Filip De Keyser Journal: Ann Rheum Dis Date: 2006-07-13 Impact factor: 19.103
Authors: B Vander Cruyssen; I E A Hoffman; H Zmierczak; M Van den Berghe; E Kruithof; L De Rycke; H Mielants; E M Veys; D Baeten; F De Keyser Journal: Ann Rheum Dis Date: 2005-02-04 Impact factor: 19.103
Authors: Choong Won Kim; Eun Hye Cho; Yun Jong Lee; Yoon Hee Kim; Young Sool Hah; Deok Ryong Kim Journal: J Korean Med Sci Date: 2006-06 Impact factor: 2.153
Authors: O Vittecoq; B Incaurgarat; F Jouen-Beades; J Legoedec; O Letourneur; D Rolland; G Gervasi; J F Ménard; A Gayet; P Fardellone; A Daragon; M Jolivet; X le Loët; F Tron Journal: Clin Exp Immunol Date: 2004-01 Impact factor: 4.330
Authors: S Dubucquoi; E Solau-Gervais; D Lefranc; L Marguerie; J Sibilia; J Goetz; V Dutoit; A-L Fauchais; E Hachulla; R-M Flipo; L Prin Journal: Ann Rheum Dis Date: 2004-04 Impact factor: 19.103