Immunology: late phase of type I hypersensitivity: 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: late phase of type I hypersensitivity

Sample item

A 25-year-old with allergic rhinitis develops an immediate wheal after a skin-prick test with grass pollen. Six hours later the site becomes swollen, firm and tender again. Which cells and mediators mainly account for this second phase?

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

The answer and the reasoning

D. Eosinophils, basophils and Th2 cells releasing leukotrienes and cytokines

The late-phase reaction of type I hypersensitivity appears several hours after the immediate wheal. It is driven by recruited eosinophils, basophils and Th2 cells together with leukotrienes and cytokines, and it follows the IgE-mediated mast cell phase.

Option by option

  • A. Neutrophils recruited by immune complexes and complement

    Immune complex neutrophilic injury describes the Arthus (type III) reaction, which is not preceded by an IgE wheal.

  • B. Cytotoxic T cells killing antigen-bearing keratinocytes

    Cytotoxic T cell killing belongs to cell-mediated type IV injury and not to this IgE sequence.

  • C. Macrophages organising a granuloma around the antigen

    Granuloma formation takes weeks and is a chronic type IV response.

  • D. Eosinophils, basophils and Th2 cells releasing leukotrienes and cytokines (correct)

    Correct. The late phase is a cellular inflammatory phase with eosinophils, basophils and Th2 cells.

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.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Eosinophils, basophils and Th2 cells releasing leukotrienes and cytokines. The late-phase reaction of type I hypersensitivity appears several hours after the immediate wheal.

Why is "Neutrophils recruited by immune complexes and complement" not the answer?

Immune complex neutrophilic injury describes the Arthus (type III) reaction, which is not preceded by an IgE wheal.

Why is "Cytotoxic T cells killing antigen-bearing keratinocytes" not the answer?

Cytotoxic T cell killing belongs to cell-mediated type IV injury and not to this IgE sequence.

Why is "Macrophages organising a granuloma around the antigen" not the answer?

Granuloma formation takes weeks and is a chronic type IV response.

What concept does this question test?

It tests Immunology: late phase of type I hypersensitivity in Microbiology. It is driven by recruited eosinophils, basophils and Th2 cells together with leukotrienes and cytokines, and it follows the IgE-mediated mast cell phase.

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: late phase of type I hypersensitivity?

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.