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Development of an in vitro model system for studying the interaction of Equus caballus IgE with its high-affinity receptor FcεRI
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Functional consequences of FcepsilonRIalpha up-regulation by IgE in human basophils

D MacGlashan1, J T Schroeder

  • 1Johns Hopkins Asthma and Allergy Center, Baltimore, Maryland 21224, USA. dmacglas@welch.jhu.edu

Journal of Leukocyte Biology
|October 19, 2000
PubMed

Insights

Human basophils showed increased responsiveness to antigen challenges after immunoglobulin E (IgE) up-regulation. However, this functional change was modulated, as not all signaling pathway components were balanced.

Area of Science:

  • Immunology
  • Cell Biology

Background:

  • Human basophils express the high-affinity IgE receptor (FcεRIα).
  • IgE binding to FcεRIα can lead to basophil activation and mediator release.

Purpose of the Study:

  • To investigate functional changes in human basophils following FcεRIα up-regulation induced by IgE.
  • To determine if FcεRIα up-regulation is coordinated with other components of the IgE signaling pathway.

Main Methods:

  • Human basophils were cultured with or without IgE antibodies for one week.
  • Cells were challenged with anti-IgE, anti-FcεRIα, or specific antigen to measure histamine and IL-4 secretion.
  • Basophil sensitivity was assessed to evaluate signaling pathway component coordination.

Main Results:

  • FcεRIα expression increased approximately 4-fold, but responses to anti-IgE or anti-receptor antibodies did not significantly change.
  • Basophils exhibited enhanced responsiveness to antigenic challenge, particularly at suboptimal antigen concentrations.
  • Increased antigen potency and histamine release were observed with higher cell surface IgE density, with similar trends for IL-4 secretion.
  • FcεRIα up-regulation was not always accompanied by coordinated changes in other signaling pathway components, affecting basophil sensitivity.

Conclusions:

  • Up-regulation of FcεRIα in human basophils leads to functional changes, including increased responsiveness to antigen.
  • The magnitude of functional up-regulation is modulated due to imbalanced up-regulation of signaling pathway components.
  • This suggests that coordinated regulation of the entire IgE signaling pathway is crucial for maintaining basophil sensitivity.

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