Volume 1 Supplement 1

Abstracts of the 50th Workshop for Pediatric Research

Open Access

Molecular dissection of human B-cell tolerance – insights from patients with rare genetic diseases

  • Henner Morbach1, 2,
  • Greta Meyers2,
  • Yen-Shing Ng2,
  • Jean-Nicolas Schickel2,
  • Laurence Menard1,
  • Sergei Rudchenko3,
  • Jessica L Rojas4,
  • Charlotte Cunningham-Rundles5,
  • Mary Ellen Conley6,
  • Ismail Reisli7,
  • Jose Luis Franco4 and
  • Eric Meffre1
Molecular and Cellular Pediatrics20141(Suppl 1):A16

DOI: 10.1186/2194-7791-1-S1-A16

Published: 11 September 2014

B cells play a central role in the pathogenesis of many autoimmune diseases. Therefore, understanding the mechanisms that regulate B-cell tolerance in humans is important for the development of new therapeutic strategies. Patients with monogenic diseases provide rare opportunities to study the impact of specific gene mutations on the regulation of human B cell tolerance. By this, we could show that alterations in B-cell receptor and Toll-like receptor (TLR) signaling pathways result in defective central B-cell tolerance.

To further dissect the signaling pathways involved in the establishment of central B-cell tolerance in humans, we tested by ELISA and immunofluorescence the reactivity of recombinant antibodies cloned from single transitional B cells from individuals carrying CD19 mutations. CD19 is a co-receptor expressed on B cells and is involved in the amplification of B-cell responses.

We found that individuals carrying CD19 mutations displayed defective central B-cell tolerance checkpoints. In addition, CD19-deficient transitional B cells were enriched in anti-nuclear clones, a feature previously observed in IRAK4- and MYD88-deficient patients in which TLR7/9 sensing nucleic acids cannot signal. Therefore, we investigated the functions of these TLRs in B cells in the absence of CD19 expression. CD19-deficient human B cells displayed defective up-regulation of activation markers after TLR7/9 triggering and failed to induce BTK, AKT but not p38 MAPK or Iκ-Bα phosphorylation after TLR7/9 stimulation. Additionally, inhibitors blocking BTK, AKT and PI3K function impaired CD19-dependent TLR7/9 responses in healthy donor’s B cells. Finally, we demonstrated that individuals carrying BTK mutations display similar defects in TLR7/9-induced B-cell activation and central B-cell tolerance.

Hence, we identified a previously unsuspected role for CD19 molecules in regulating TLR7/9 functions in human B cells and central B-cell tolerance to nuclear antigens.

Authors’ Affiliations

(1)
University Children’s Hospital
(2)
Department of Immunobiology, Yale University School of Medicine
(3)
Laboratory of Biochemistry and Molecular Immunology, Hospital for Special Surgery
(4)
Group of Primary Immunodeficiencies, University of Antioquia
(5)
Department of Medicine, Mount Sinai Medical Center
(6)
Department of Pediatrics, University of Tennessee College of Medicine
(7)
Department of Immunology and Allergy, Meram Medical Faculty, Selcuk University

Copyright

© Morbach et al; licensee Springer 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.