Specificity of Anti-Citrullinated Protein Antibodies in Rheumatoid Arthritis

• Published in: Antibodies (Basel) Vol. 8; no. 2; p. 37
• Main Authors: Trier, Nicole H., Holm, Bettina E., Hansen, Paul R., Slot, Ole, Locht, Henning, Houen, Gunnar
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2019; MDPI
• Subjects: Amino acids; anti-citrullinated protein antibodies; Antibodies; Antigens; Arginine; Arthritis; Autoimmune diseases; Binding sites; Citrulline; Disease; Epitopes; Etiology; homo-citrulline; Immunoassays; Immunoglobulins; Peptides; Post-translation; Proteins; Rheumatoid arthritis; Rheumatology; Studies; Denmark; United States > US
• ISSN: 2073-4468; 2073-4468
• DOI: 10.3390/antib8020037

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology. The majority of individuals with RA are positive for the disease-specific anti-citrullinated protein antibodies (ACPAs). These antibodies are primarily of cross-reactive nature, hence, the true autoantigen to ACPA remains unidentified. In this study, we analyzed the reactivity of RA sera to several post-translationally modified epitopes, in order to further characterize the specific nature of ACPAs by immunoassays. Substituting citrulline with other amino acids, e.g., D-citrulline, homo-citrulline and methyl-arginine illustrated that ACPAs are utmost specific for citrullinated targets. Collectively, these findings support that ACPAs and citrullinated targets are specific for RA, making citrulline-containing peptide targets the most effective assays for detection of ACPAs.