Antibody deficiency in patients with ataxia telangiectasia is caused by disturbed B- and T-cell homeostasis and reduced immune repertoire diversity

Gertjan J. Driessen, Hanna Ijspeert, Corry M R Weemaes, Ásgeir Haraldsson, Margreet Trip, Adilia Warris, Michiel Van Der Flier, Nico Wulffraat, Mijke M M Verhagen, Malcolm A. Taylor, Menno C. Van Zelm, Jacques J M Van Dongen, Marcel Van Deuren, Mirjam Van Der Burg

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Abstract

Background: Ataxia telangiectasia (AT) is a multisystem DNA-repair disorder caused by mutations in the ataxia telangiectasia mutated (ATM) gene. Patients with AT have reduced B- and T-cell numbers and a highly variable immunodeficiency. ATM is important for V(D)J recombination and immunoglobulin class-switch recombination (CSR); however, little is known about the mechanisms resulting in antibody deficiency severity. Objective: We sought to examine the immunologic mechanisms responsible for antibody deficiency heterogeneity in patients with AT. Methods: In this study we included patients with classical AT plus early-onset hypogammaglobulinemia (n = 3), classical AT (n = 8), and variant AT (late onset, n = 4). We studied peripheral B- and T-cell subsets, B-cell subset replication history, somatic hypermutation frequencies, CSR patterns, B-cell repertoire, and ATM kinase activity. Results: Patients with classical AT lacked ATM kinase activity, whereas patients with variant AT showed residual function. Most patients had disturbed naive B-cell and T-cell homeostasis, as evidenced by low cell numbers, increased proliferation, a large proportion CD21lowCD38low anergic B cells, and decreased antigen receptor repertoire diversity. Impaired formation of T cell-dependent memory B cells was predominantly found in patients with AT plus hypogammaglobulinemia. These patients had extremely low naive CD4+ T-cell counts, which were more severely reduced compared with those seen in patients with classical AT without hypogammaglobulinemia. Finally, AT deficiency resulted in defective CSR to distal constant regions that might reflect an impaired ability of B cells to undergo multiple germinal center reactions. Conclusion: The severity of the antibody deficiency in patients with AT correlates with disturbances in B- and T-cell homeostasis resulting in reduced immune repertoire diversity, which consequently affects the chance of successful antigen-dependent cognate B-T interaction.

Original languageEnglish
JournalJournal of Allergy and Clinical Immunology
Volume131
Issue number5
DOIs
Publication statusPublished - May 2013
Externally publishedYes

Keywords

  • κ-deleting recombination excision circle
  • Ataxia telangiectasia
  • B-cell subsets
  • class switch recombination
  • hypogammaglobulinemia
  • somatic hypermutation
  • T-cell subsets

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