IgE Antibodies: Structure, Function, and Role in Allergies

Structure

IgE has two ε heavy chains and two light chains. Fc region binds immune cell receptors; Fab region binds allergens.

Production

Plasma cells produce IgE upon antigen exposure; regulated by IL-4.

Allergic Reaction Mechanism

1. Sensitization: First exposure → allergen-specific IgE produced.
2. Binding: IgE attaches to mast cell receptors.
3. Degranulation: Re-exposure cross-links IgE → mast cells release histamine, leukotrienes.
4. Symptoms: Sneezing, itching, wheezing, anaphylaxis.

Parasite Defense

IgE binds parasites, recruits eosinophils, releases cytotoxic chemicals.

Clinical Significance

Elevated IgE correlates with asthma, hay fever, eczema, food allergies. IgE testing identifies specific allergens for diagnosis/management.