title: Intrinsic properties of germinal center-derived B cells promote their enhanced class switching to IgE.
abstract: BACKGROUND
  Research on the origins and development of human IgE-expressing (IgE(+) ) cells is required for understanding the pathogenesis of allergy and asthma. These studies have been thwarted by the rarity of IgE(+) cells in vivo and the low frequency of class switch recombination (CSR) to IgE ex vivo. To determine the main source of IgE(+) cells, we investigated the relation between the phenotypic composition of tonsil B cells and the CSR to IgE ex vivo.
  
  
  METHODS
  Human tonsil B cells were analyzed by flow cytometry (FACS) and cultured with IL-4 and anti-CD40 to induce CSR to IgE. Naïve, germinal center (GC), early GC (eGC), and memory tonsil B cells were isolated by FACS, and their capacities for IL-4 and anti-CD40 signaling, cell proliferation, and de novo class switching to IgE were analyzed by RT-PCR and FACS.
  
  
  RESULTS
  B cells from different tonsils exhibited varying capacities for CSR to IgE ex vivo. This was correlated with the percentage of eGC B cells in the tonsil at the outset of the culture. Despite relatively poor cell viability, eGC and GC B-cell cultures produced the highest yields of IgE(+) cells compared to naïve and memory B-cell cultures. The main factors accounting for this result were the strength of IL-4R and CD40 signaling and relative rates of cell proliferation.
  
  
  CONCLUSIONS
  This study shows that the maturation state of tonsil B cells determines their capacity to undergo class switching to IgE ex vivo, with the GC-derived B cells yielding the highest percentage of IgE(+) cells.
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: F
authors.identifier: http://orcid.org/0000-0001-8228-4868
authors.initials: F
authors.lastname: Ramadani
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Upton
authors.affiliation: Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: P
authors.initials: P
authors.lastname: Hobson
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: Y-C
authors.initials: YC
authors.lastname: Chan
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Mzinza
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Bowen
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Kerridge
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: B J
authors.initials: BJ
authors.lastname: Sutton
authors.affiliation: Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Fear
authors.affiliation: Randall Division of Cell and Molecular Biohphysics, King's College London, London, UK.|Medical Research Council and Asthma UK Centre, Allergic Mechanisms in Asthma, London, UK.
authors.forename: H J
authors.initials: HJ
authors.lastname: Gould
mesh_terms: D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D019013:CD40 Antigens / Q000037:antagonists & inhibitors / Q000378:metabolism; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D018858:Germinal Center / Q000166:cytology*; D006801:Humans; D017578:Immunoglobulin Class Switching / Q000235:genetics* / Q000276:immunology*; D007073:Immunoglobulin E / Q000235:genetics* / Q000276:immunology*; D007156:Immunologic Memory; D015847:Interleukin-4 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D018655:Lymphocyte Count; D014066:Palatine Tonsil / Q000166:cytology; D015398:Signal Transduction
chemical_list: D019013:CD40 Antigens; D015847:Interleukin-4; D007073:Immunoglobulin E
keywords: IgE class switching; allergy; germinal center; human B cells