IgE

Overview

IgE is a particular isotype of Antibody (see page). Production of IgE is thought to be a critical step in the pathogenesis of certain allergic responses.

Structure

Function

Few immune responses result in synthesis of the IgE isotype. However, the IgE isotype is often produced in responses to parasitic infections and thus is thought to play a role in anti-parasitic immunity. Consistent with this, IgE antibodies are bound by Fc Receptors on the anti-parasitic leukocytes, Mast Cells, Basophils, and Eosinophils. Unlike other antibody isotypes, IgE is bound by its Fc Receptor even when not cross-linked with antigen. Consequently, the anti-parasitic leukocytes will possess membrane-bound IgE on their surface even in the absence of antigen.
When antigen is present, cross-linking of membrane-bound IgE on the anti-parasitic leukocytes results in their degranulation which releases a wide variety of vasoactive and bronchoactive mediators. Inappropriate IgE-mediated degranulation to environmental antigens is thought to be the basis of certain allergic responses which is considered a Type I Hypersensitivity. In some cases, degranulation can be wide-spread and catastrophic, resulting in Anaphylactic Shock.

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