Decreased somatic hypermutation induces an impaired peripheral B cell tolerance checkpoint

• Published in: The Journal of clinical investigation Vol. 126; no. 11; pp. 4289 - 4302
• Main Authors: Cantaert, Tineke, Schickel, Jean-Nicolas, Bannock, Jason M., Ng, Yen-Shing, Massad, Christopher, Delmotte, Fabien R., Yamakawa, Natsuko, Glauzy, Salome, Chamberlain, Nicolas, Kinnunen, Tuure, Menard, Laurence, Lavoie, Aubert, Walter, Jolan E., Notarangelo, Luigi D., Bruneau, Julie, Al-Herz, Waleed, Kilic, Sara Sebnem, Ochs, Hans D., Cunningham-Rundles, Charlotte, van der Burg, Mirjam, Kuijpers, Taco W., Kracker, Sven, Kaneko, Hideo, Sekinaka, Yujin, Nonoyama, Shigeaki, Durandy, Anne, Meffre, Eric
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.11.2016
• Subjects: Analysis; Autoimmunity; B cells; B-Lymphocytes - immunology; B-Lymphocytes - pathology; Biomedical research; Cell Cycle Checkpoints - genetics; Cell Cycle Checkpoints - immunology; Cloning; Cytidine Deaminase - deficiency; Cytidine Deaminase - immunology; Cytokines; Defects; Experiments; Female; Gene mutations; Health aspects; Humans; Immune Tolerance; Immunoglobulins; Immunologic Memory; Interleukins; Lymphocyte receptors; Male; Mutation; Physiological aspects; R&D; Research & development; Somatic Hypermutation, Immunoglobulin - immunology; Studies; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - pathology; Massachusetts
• ISSN: 0021-9738; 1558-8238; 1558-8238
• DOI: 10.1172/JCI84645

Patients with mutations in AICDA, which encodes activation-induced cytidine deaminase (AID), display an impaired peripheral B cell tolerance. AID mediates class-switch recombination (CSR) and somatic hypermutation (SHM) in B cells, but the mechanism by which AID prevents the accumulation of autoreactive B cells in blood is unclear. Here, we analyzed B cell tolerance in AID-deficient patients, patients with autosomal dominant AID mutations (AD-AID), asymptomatic AICDA heterozygotes (AID+/-), and patients with uracil N-glycosylase (UNG) deficiency, which impairs CSR but not SHM. The low frequency of autoreactive mature naive B cells in UNG-deficient patients resembled that of healthy subjects, revealing that impaired CSR does not interfere with the peripheral B cell tolerance checkpoint. In contrast, we observed decreased frequencies of SHM in memory B cells from AD-AID patients and AID+/- subjects, who were unable to prevent the accumulation of autoreactive mature naive B cells. In addition, the individuals with AICDA mutations, but not UNG-deficient patients, displayed Tregs with defective suppressive capacity that correlated with increases in circulating T follicular helper cells and enhanced cytokine production. We conclude that SHM, but not CSR, regulates peripheral B cell tolerance through the production of mutated antibodies that clear antigens and prevent sustained interleukin secretions that interfere with Treg function.