Question

Hypersensitivity - I is associated with what type of immune complex? (Note: Type I Hypersensitivity is immediate hypersensitivity / allergy.)

• A. IgM antibody + Protein antigen complex
• B. IgG antibody + Protein antigen complex
• C. IgE antibody + Allergen complex
• D. IgA antibody + antigen complex

Hint:

• Type I (Allergy/Anaphylaxis) IgE-mediated, mast cell degranulation (Histamine). Allergen binds to IgE on mast cells.
• Type II (Cytotoxic) IgG/IgM against cell surface/matrix antigens. Complement activation, phagocytosis.
• Type III (Immune Complex) IgG/IgM immune complexes deposit in tissues. Complement, inflammation.
• Type IV (Delayed-Type) T cell-mediated (T\(_H\)1, CTLs). Cytokines, inflammation. No antibodies involved directly.

Answer 1

The Correct Option is C

Type I Hypersensitivity, commonly known as immediate hypersensitivity or allergy, involves an immune response that is mediated by IgE antibodies. This type of reaction occurs when the immune system overreacts to a harmless substance known as an allergen.

In Type I Hypersensitivity, the IgE antibodies bind to the allergens. These IgE-allergen complexes then attach to the surface of mast cells and basophils, causing them to release histamines and other chemicals. This release leads to the symptoms associated with allergic reactions, such as itching, swelling, and redness.

Hence, the immune complex associated with Type I Hypersensitivity is the IgE antibody + Allergen complex.