Blood and immunity: superantigens: practice question

A Physiology 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

Physiology · Blood and immunity: superantigens

Sample item

A young woman using a tampon develops fever, a diffuse rash and hypotension. The responsible toxin binds MHC class II outside the peptide groove and the T-cell receptor beta chain, activating a large fraction of all T cells. What is the effect?

AMassive polyclonal T-cell activation with a surge of cytokinesBSelective suppression of regulatory T cells onlyCBlockade of antibody production by B cellsDAntigen-specific activation of a single T-cell clone

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

The answer and the reasoning

A. Massive polyclonal T-cell activation with a surge of cytokines

Superantigens bridge MHC class II and the variable region of the T-cell receptor beta chain without antigen processing. This activates a large fraction of T cells at once and releases interleukin-2, interferon-gamma and TNF, leading to the shock of toxic shock syndrome.

Option by option

A. Massive polyclonal T-cell activation with a surge of cytokines (correct)
Correct. Polyclonal activation releases a cytokine storm and shock.
B. Selective suppression of regulatory T cells only
Regulatory T cells are not selectively suppressed; the dominant effect is widespread activation.
C. Blockade of antibody production by B cells
The toxin activates T cells, and B cell antibody production is not blocked.
D. Antigen-specific activation of a single T-cell clone
Conventional antigen binds the groove and activates one clone, not a large fraction of all T 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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Massive polyclonal T-cell activation with a surge of cytokines. Superantigens bridge MHC class II and the variable region of the T-cell receptor beta chain without antigen processing.

Why is "Selective suppression of regulatory T cells only" not the answer?

Regulatory T cells are not selectively suppressed; the dominant effect is widespread activation.

Why is "Blockade of antibody production by B cells" not the answer?

The toxin activates T cells, and B cell antibody production is not blocked.

Why is "Antigen-specific activation of a single T-cell clone" not the answer?

Conventional antigen binds the groove and activates one clone, not a large fraction of all T cells.

What concept does this question test?

It tests Blood and immunity: superantigens in Physiology. This activates a large fraction of T cells at once and releases interleukin-2, interferon-gamma and TNF, leading to the shock of toxic shock syndrome.

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 Blood and immunity: superantigens?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.