Journal Article

Adaptive antibody diversification through N-linked glycosylation of the immunoglobulin variable region

Heer, Pleuni Ooijevaar-de, Kruithof, Simone, Berkowska, Magdalena A., van der Burg, Mirjam, Toes, René E. M., Rombouts, Yoann, Rispens, Theo, Plomp, Rosina, Derksen, Ninotska I. L., van Schie, Karin A., van der Schoot, C. Ellen, Hafkenscheid, Lise, Gils, Ann, van Ham, S. Marieke, van de Bovenkamp, Fleur S., Wuhrer, Manfred, IJspeert, Hanna, Vidarsson, Gestur

2018

Overview

A hallmark of B-cell immunity is the generation of a diverse repertoire of antibodies from a limited set of germline V(D)J genes. This repertoire is usually defined in terms of amino acid composition. However, variable domains may also acquire N-linked glycans, a process conditional on the introduction of consensus amino acid motifs (N-glycosylation sites) during somatic hypermutation. High levels of variable domain glycans have been associated with autoantibodies in rheumatoid arthritis, as well as certain follicular lymphomas. However, the role of these glycans in the humoral immune response remains poorly understood. Interestingly, studies have reported both positive and negative effects on antibody affinity. Our aim was to elucidate the role of variable domain glycans during antigen-specific antibody responses. By analyzing B-cell repertoires by next-generation sequencing, we demonstrate that N-glycosylation sites are introduced at positions in which glycans can affect antigen binding as a result of a specific clustering of progenitor glycosylation sites in the germline sequences of variable domain genes. By analyzing multiple human monoclonal and polyclonal (auto)antibody responses, we subsequently show that this process is subject to selection during antigen-specific antibody responses, skewed toward IgG4, and positively contributes to antigen binding. Together, these results highlight a physiological role for variable domain glycosylation as an additional layer of antibody diversification that modulates antigen binding.

• Publisher: National Academy of Sciences
• Subject: Amino acid composition / Amino acids / Antibodies / Antibodies, Monoclonal / Antibody Affinity / Arthritis / Arthritis, Rheumatoid - immunology / Autoantibodies / B-Lymphocytes - metabolism / Binding / Biological Sciences / Clustering / Gene sequencing / Genes / Glycosylation / Humans / Immune response / Immune response (humoral) / Immune system / Immunity / Immunoglobulin G / Immunoglobulin G - genetics / Immunoglobulin Variable Region - genetics / Immunoglobulins / Immunology and Inflammation / Life Sciences / Lymphocytes B / Lymphoma / N-glycans / Phosphorylation / Polysaccharides / Rheumatoid arthritis / Somatic hypermutation / Variable region / Variables