Immunology: Prausnitz-Kustner reaction: 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.

Try it

Microbiology · Immunology: Prausnitz-Kustner reaction

Sample item

In the classical Prausnitz-Kustner experiment, serum from a fish-allergic person was injected into the skin of a non-allergic volunteer. A day later, fish extract injected at the same site produced a wheal and flare. Which serum factor was transferred?

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

The answer and the reasoning

D. IgE (reaginic antibody)

Serum IgE binds to Fc epsilon receptors on the volunteer's skin mast cells, so later contact with allergen causes degranulation and an immediate wheal. This showed that type I hypersensitivity can be passively transferred by serum. Delayed hypersensitivity, by contrast, can be transferred by cells and not by serum.

Option by option

  • A. Complement C3

    C3 is not an antibody and does not sensitise mast cells for allergen-specific reactions.

  • B. Sensitised T lymphocytes

    Cells would transfer delayed hypersensitivity, and serum contains no sensitised T cells.

  • C. IgM antibodies

    IgM does not bind mast cell receptors in this way.

  • D. IgE (reaginic antibody) (correct)

    Correct. Transferred IgE sensitises recipient mast cells, producing the wheal and flare.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, IgE (reaginic antibody). Serum IgE binds to Fc epsilon receptors on the volunteer's skin mast cells, so later contact with allergen causes degranulation and an immediate wheal.

Why is "Complement C3" not the answer?

C3 is not an antibody and does not sensitise mast cells for allergen-specific reactions.

Why is "Sensitised T lymphocytes" not the answer?

Cells would transfer delayed hypersensitivity, and serum contains no sensitised T cells.

Why is "IgM antibodies" not the answer?

IgM does not bind mast cell receptors in this way.

What concept does this question test?

It tests Immunology: Prausnitz-Kustner reaction in Microbiology. This showed that type I hypersensitivity can be passively transferred by serum. Delayed hypersensitivity, by contrast, can be transferred by cells and not by serum.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: Prausnitz-Kustner reaction?

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.