Apoptosis: cytotoxic T-cell killing: practice question

A Pathology 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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Pathology · Apoptosis: cytotoxic T-cell killing

Sample item

A virus-infected hepatocyte is destroyed by a CD8+ cytotoxic T lymphocyte. Which mechanism triggers apoptosis of the target cell?

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

The answer and the reasoning

D. Perforin forms pores through which granzymes enter and activate caspases

A CTL recognises viral peptide on MHC class I and releases perforin and granzymes from its granules. Perforin creates pores, granzymes enter and activate the caspase cascade, and the target dies by apoptosis. CTLs can also engage Fas on the target through Fas ligand.

Option by option

  • A. Antibody-coated cell uptake by neutrophils through Fc receptors

    Fc receptor mediated uptake of antibody-coated cells is an antibody dependent mechanism of phagocytes.

  • B. Burst of reactive oxygen species by NADPH oxidase

    NADPH oxidase generates oxidants in phagocytes to kill ingested microbes.

  • C. Membrane attack complex assembly by complement C5b-9

    Membrane attack complex lysis is a complement effector mechanism and does not involve T cells.

  • D. Perforin forms pores through which granzymes enter and activate caspases (correct)

    Correct. Perforin and granzyme delivery is the main CTL killing mechanism.

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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Perforin forms pores through which granzymes enter and activate caspases. A CTL recognises viral peptide on MHC class I and releases perforin and granzymes from its granules.

Why is "Antibody-coated cell uptake by neutrophils through Fc receptors" not the answer?

Fc receptor mediated uptake of antibody-coated cells is an antibody dependent mechanism of phagocytes.

Why is "Burst of reactive oxygen species by NADPH oxidase" not the answer?

NADPH oxidase generates oxidants in phagocytes to kill ingested microbes.

Why is "Membrane attack complex assembly by complement C5b-9" not the answer?

Membrane attack complex lysis is a complement effector mechanism and does not involve T cells.

What concept does this question test?

It tests Apoptosis: cytotoxic T-cell killing in Pathology. Perforin creates pores, granzymes enter and activate the caspase cascade, and the target dies by apoptosis. CTLs can also engage Fas on the target through Fas ligand.

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 Apoptosis: cytotoxic T-cell killing?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.