Question

Following a bee sting, the person develops periorbital edema, laryngospasm, breathing difficulty. These reactions are mediated through which of the following?

• A. Cytotoxic T cell
• B. IgE mediated
• C. IgA mediated
• D. Immune complex reactions

Hint:

Immediate swelling and breathing trouble after a sting is anaphylaxis, a Type I hypersensitivity reaction driven by IgE on mast cells.

Answer 1

The Correct Option is B

A bee sting followed within minutes by periorbital swelling, laryngospasm and breathing difficulty is a textbook picture of anaphylaxis. Let's check which immune mechanism fits.

1. Cytotoxic T cell: This drives Type IV delayed hypersensitivity, which takes a day or more to show up, such as contact dermatitis, so it does not fit a reaction happening within minutes.
2. IgE mediated: On an earlier sting the body makes IgE against venom proteins, which sit on mast cells. A repeat sting cross links this IgE, the mast cells degranulate at once, and histamine plus other mediators cause the swelling and airway spasm seen here, so this fits perfectly.
3. IgA mediated: IgA mainly guards mucosal surfaces like the gut and airway lining, it is not the antibody behind immediate allergic reactions.
4. Immune complex reactions: This is Type III hypersensitivity, where antigen antibody complexes settle in tissue and trigger complement over hours to days, again too slow for this presentation.

The correct option is IgE mediated, since only a Type I, IgE driven, mast cell reaction can produce symptoms this fast after a sting.

Let's summarize:

• Fast reactions within minutes of exposure point to Type I hypersensitivity, mediated by IgE and mast cells.
• Cytotoxic T cell, immune complex and IgA driven mechanisms all act over a longer time frame, so they do not fit here.

So the reactions after the bee sting are IgE mediated.