SPR-based biosensor analysis of autoantibodies from Rheumatoid Arthritis patients’ sera interacting with citrullinated Multiple Antigen Peptides

Anti-Citrullinated Protein/Peptide Antibodies (ACPAs). ACPAs recognize different self proteins, such as filaggrin, fibrinogen, vimentin, enolase and histone H4 [1], but also exogenous sequences derived from Epstein-Barr Virus (EBV)-encoded proteins [2] the arginyl residues of which have been post-translationally deiminated into citrullyl residues. Because of their high disease specificity, ACPAs are considered marker antibodies [3] and they are monitored in patients’ sera through diagnostic immunoassays employing citrullinated cyclic peptides (CCPs) as gold standard probes. The association of ACPAs with erosive arthritis has suggested a role of the antibodies in inducing inflammation and joint damage and antibody affinity is known to be one of the parameters affecting pathogenicity. In this work the Surface Plasmon Resonance (SPR) biosensor Biacore has been employed with the aim of revealing and characterizing the affinity and the kinetic of the interaction between purified ACPAs and three citrullinated Multiple Antigen Peptides (MAPs)