Human blood basophils do not act as antigen-presenting cells for the major birch pollen allergen Bet v 1

Allergy. 2012 May;67(5):593-600. doi: 10.1111/j.1398-9995.2011.02764.x. Epub 2011 Dec 20.

Abstract

Background: Several studies in mice have recently shown that basophils can act as antigen-presenting cells (APC) inducing Th2-mediated immune responses against parasites or protease allergens. The aim of this study was to investigate whether human basophils function as APC for the major birch pollen allergen Bet v 1.

Methods: Fluorescently labeled Bet v 1 was used to assess surface binding and internalization of allergen by basophils and different types of APC from birch pollen-allergic and nonallergic individuals. Sorted basophils were analyzed in terms of up-regulation of MHC class II and co-stimulatory molecules in the absence and presence of IL-3 and IFN-γ by flow cytometry. Expression of proteins crucial for antigen presentation, namely cathepsin S and invariant chain, was determined. Basophils were used as APC in co-culture experiments with Bet v 1-specific T-cell clones (TCCs).

Results: Basophils from birch pollen-allergic donors very efficiently bound Bet v 1 through IgE/FcεRI complexes on their surface. In contrast to professional APC, basophils did not internalize allergen and expressed marginal levels of cathepsin S and invariant chain. HLA-DP, HLA-DQ, CD80/CD86, and CD40 were absent from purified basophils even when stimulated with IL-3 plus IFN-γ. IL-3/IFN-γ marginally up-regulated HLA-DR. Bet v 1-pulsed basophils failed to induce proliferative and cytokine responses in Bet v 1-specific, HLA-DR-restricted TCCs.

Conclusion: Human basophils neither internalize, process nor present Bet v 1. Because Bet v 1 is a highly relevant allergen, we conclude that basophils play no role as APC in IgE-mediated allergy in humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens / immunology*
  • Antigen-Presenting Cells / immunology*
  • Antigens, Plant / immunology*
  • Antigens, Plant / metabolism
  • Basophils / immunology*
  • Basophils / metabolism
  • Endocytosis / immunology
  • Epitopes / immunology
  • Histocompatibility Antigens Class II / immunology
  • Histocompatibility Antigens Class II / metabolism
  • Humans
  • Hypersensitivity, Immediate / immunology
  • Hypersensitivity, Immediate / metabolism
  • Pollen / immunology*
  • Protein Binding / immunology
  • Receptors, IgE / immunology
  • Receptors, IgE / metabolism
  • T-Lymphocytes / immunology

Substances

  • Allergens
  • Antigens, Plant
  • Epitopes
  • Histocompatibility Antigens Class II
  • Receptors, IgE
  • Bet v 1 allergen, Betula