Question

Which one of the following antibodies initiates an allergic reaction

• A. IgA
• B. IgE
• C. IgG
• D. IgM

Answer 1

Answer: (B)

IgE

Human immunoglobulin E (IgE) is expressed on the surface of mature B cells. Human immunoglobulin IgE is the least abundant Ig in the serum and does not activate the complement pathway. Fragment crystallization (Fc) receptors for IgE are found on eosinophils and IgE binds Fc receptors on mast cells and basophils even before interacting with antigen. As a result of its binding to basophils and mast cells, IgE is involved in allergic reactions. This happens when allergen is bound to IgE on cells and releases various pharmacological mediators which cause allergies.

So, the correct option is 'Option B'.