Immunology: mechanism of allergen immunotherapy: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Immunology: mechanism of allergen immunotherapy

Sample item

A beekeeper with a history of systemic reactions to stings completes a course of venom immunotherapy and tolerates a sting without anaphylaxis. Which immunological change best accounts for the protection?

ARise in allergen-specific IgE bound to mast cellsBDepletion of circulating basophilsCPermanent loss of Fc epsilon receptors from mast cellsDRise in allergen-specific IgG4 and regulatory T cell activity

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Rise in allergen-specific IgG4 and regulatory T cell activity

Repeated administration of increasing allergen doses shifts the response from Th2 towards regulatory T cell activity with IL-10, and induces allergen-specific IgG4 that blocks allergen before it reaches IgE on mast cells. Specific IgE often rises transiently and then falls, and mast cells are not destroyed.

Option by option

A. Rise in allergen-specific IgE bound to mast cells
Higher IgE on mast cells would increase the risk of reaction rather than protect.
B. Depletion of circulating basophils
Basophils are not depleted by immunotherapy; the effect is mediated by changes in antibody and T cell responses.
C. Permanent loss of Fc epsilon receptors from mast cells
Mast cell Fc epsilon receptors are not permanently lost during immunotherapy.
D. Rise in allergen-specific IgG4 and regulatory T cell activity (correct)
Correct. Blocking IgG4 and regulatory T cell activity underlie the tolerance.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Rise in allergen-specific IgG4 and regulatory T cell activity. Repeated administration of increasing allergen doses shifts the response from Th2 towards regulatory T cell activity with IL-10, and induces allergen-specific IgG4 that blocks allergen before it reaches IgE on mast cells.

Why is "Rise in allergen-specific IgE bound to mast cells" not the answer?

Higher IgE on mast cells would increase the risk of reaction rather than protect.

Why is "Depletion of circulating basophils" not the answer?

Basophils are not depleted by immunotherapy; the effect is mediated by changes in antibody and T cell responses.

Why is "Permanent loss of Fc epsilon receptors from mast cells" not the answer?

Mast cell Fc epsilon receptors are not permanently lost during immunotherapy.

What concept does this question test?

It tests Immunology: mechanism of allergen immunotherapy in Microbiology. Specific IgE often rises transiently and then falls, and mast cells are not destroyed.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Immunology: mechanism of allergen immunotherapy?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.