Monoclonal IgG antibodies generated from joint-derived B cells of RA patients have a strong bias toward citrullinated autoantigen recognition

Abstract

<jats:p>Antibodies targeting citrullinated proteins (ACPAs [anticitrullinated protein antibodies]) are commonly found in patients with rheumatoid arthritis (RA), strongly associate with distinct HLA-DR alleles, and predict a more aggressive disease course as compared with seronegative patients. Still, many features of these antibodies, including their site of production and the extent of MHC class II–driven T cell help, remain unclarified. To address these questions, we have used a single B cell–based cloning technology to isolate and express immunoglobulin (Ig) genes from joint-derived B cells of active RA patients. We found ∼25% of synovial IgG-expressing B cells to be specific for citrullinated autoantigens in the investigated ACPA+ RA patients, whereas such antibodies were not found in ACPA− patients. The citrulline-reactive monoclonal antibodies did not react with the unmodified arginine peptides, yet several reacted with more than one citrullinated antigen. A role for active antigen selection of the citrulline-reactive synovial B cells was supported by the strong bias toward amino acid replacement mutations in ACPA+ antibodies and by their loss of reactivity to citrullinated autoantigens when somatic mutations were reverted to the corresponding germline sequences.</jats:p>

Naturally Occurring Human Phosphorylcholine Antibodies Are Predominantly Products of Affinity-Matured B Cells in the Adult

“…We also assayed the polyreactivity profiles of the mAbs using an established ELISA method (21). Polyreactivity was ob- served in ∼26% of our human anti-PC mAbs (Supplemental Table II), which is in the same range of what has been reported for other specificities (26). Using surface plasmon resonance, we determined the affinity of ten mAbs to free monomeric PC-hapten, and the results were compared with the previously reported affinity of mouse T-15 (27) (Table III).…”

Antibody repertoire analysis in polygenic autoimmune diseases

“…Switching occurred primarily to IgG and IgA 114. Evidence for class‐switched autoreactive B‐cells in RA is also supported by other studies,105, 109 where ~25% of synovial IgG+ B‐cells were reactive to citrullinated autoantigens in ACPA‐positive RA patients,109 and production of ACPAs by RA peripheral blood IgG+ plasmablasts was found in ACPA+ RA patients, but not ACPA− RA or psoriatic arthritis patients 94. Tan et al .…”

“…Using single‐cell sequencing and monoclonal antibody expression of B‐cells from the joints of ACPA+ RA patients with active disease, 25% of synovial IgG‐expressing B‐cells were specific for citrullinated autoantigens; however, these were not found in ACPA‐negative RA patients 109. While some of the ACPAs bound more than one citrullinated antigen, none was reactive to non‐citrullinated antigen.…”

Immunoglobulin G Subclass Profile of Anticitrullinated Peptide Antibodies Specific for Epstein Barr Virus-derived and Histone-derived Citrullinated Peptides

“…Studies have shown that the anticitrullinated peptide antibodies (ACPA) response is highly polyclonal, in terms of epitope specificity, V genes, and isotype usage 1,2 . Longitudinal studies of patients with rheumatoid arthritis (RA) have documented epitope spreading, and ACPA, specific for distinct citrullinated epitopes, have been described.…”