Redemption of autoantibodies on anergic B cells by variable-region glycosylation and mutation away from self-reactivity

Zahra Sabouri, Peter Schofield, Keisuke Horikawa, Emily Spierings, David Kipling, Katrina L. Randall, David Langley, Brendan Roome, Rodrigo Vazquez-Lombardi, Romain Rouet, Jana Hermes, Tyani D. Chan, Robert Brink, Deborah K. Dunn-Walters, Daniel Christ, Christopher C. Goodnow

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139 Citations (Scopus)

Abstract

The best-understood mechanisms for achieving antibody self/nonself discrimination discard self-reactive antibodies before they can be tested for binding microbial antigens, potentially creating holes in the repertoire. Here we provide evidence for a complementary mechanism: retaining autoantibodies in the repertoire displayed as low levels of IgM and high IgD on anergic B cells, masking a varying proportion of autoantibody-binding sites with carbohydrates, and removing their self-reactivity by somatic hypermutation and selection in germinal centers (GCs). Analysis of human antibody sequences by deep sequencing of isotype-switched memory B cells or in IgG antibodies elicited against allogeneic RhD+ erythrocytes, vaccinia virus, rotavirus, or tetanus toxoid provides evidence for reactivation of anergic IgMlow IgD+ IGHV4-34+ B cells and removal of cold agglutinin self-reactivity by hypermutation, often accompanied by mutations that inactivated an N-linked glycosylation sequon in complementarity-determining region 2 (CDR2). In a Hy10 antibody transgenic model where anergic B cells respond to a biophysically defined lysozyme epitope displayed on both foreign and self-antigens, cell transfers revealed that anergic IgMlow IgD+ B cells form twice as many GC progeny as naïve IgMhi IgD+ counterparts. Their GC progeny were rapidly selected for CDR2 mutations that blocked 72% of antigen-binding sites with N-linked glycan, decreased affinity 100-fold, and then cleared the binding sites of blocking glycan. These results provide evidence for a mechanism to acquire self/non-self discrimination by somatic mutation away from self-reactivity, and reveal how varying the efficiency of N-glycosylation provides a mechanism to modulate antibody avidity.

Original languageEnglish
Pages (from-to)E2567-E2575
Number of pages9
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number25
DOIs
Publication statusPublished - 24 Jun 2014
Externally publishedYes

Keywords

  • Affinity maturation
  • Autoimmunity
  • Clonal selection
  • Self-tolerance

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