IgE antibodies are mainly associated with which type of hypersensitivity reaction?

• A. Type II hypersensitivity
• B. Type III hypersensitivity
• C. Type I hypersensitivity
• D. Type IV hypersensitivity

Answer: (C)

IgE antibodies are the hallmark of immediate, IgE-mediated allergic reactions, known as Type I hypersensitivity. In this type, exposure to an allergen stimulates B cells to produce IgE, which binds to receptors on mast cells and basophils. Upon re-exposure, the allergen cross-links these IgE molecules, triggering rapid degranulation and release of histamine and other mediators. This causes quick-onset symptoms such as itching, swelling, runny nose, bronchoconstriction, and, in severe cases, anaphylaxis. The other hypersensitivity types involve different antibodies (like IgG or IgM) or T-cell–driven mechanisms, not primarily IgE, so they don’t fit this pattern.