Immunology: 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

Sample item

Within minutes of reperfusion of a transplanted kidney, the graft becomes cyanosed and mottled with fibrinoid necrosis of vessels. The recipient was sensitised by multiple prior transfusions. What is the mechanism?

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

The answer and the reasoning

B. Preformed anti-donor HLA antibodies causing complement-mediated endothelial injury

Hyperacute rejection occurs within minutes to hours in a recipient with preformed antibodies, usually from transfusion, previous transplant or pregnancy. Antibodies bind donor endothelium, activate complement and cause thrombosis and necrosis. A negative cross-match prevents it.

Option by option

  • A. Chronic graft arteriopathy from repeated low-grade injury

    Chronic rejection develops over months to years with vascular intimal thickening.

  • B. Preformed anti-donor HLA antibodies causing complement-mediated endothelial injury (correct)

    Correct. Preformed antibodies and complement cause immediate endothelial injury.

  • C. Donor T cells attacking recipient tissues

    Donor T cells attacking the recipient describe graft-versus-host disease, not graft rejection.

  • D. Donor-specific cytotoxic T cells attacking graft parenchyma over weeks

    T-cell mediated attack is the mechanism of acute cellular rejection, over days to weeks.

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 B, Preformed anti-donor HLA antibodies causing complement-mediated endothelial injury. Hyperacute rejection occurs within minutes to hours in a recipient with preformed antibodies, usually from transfusion, previous transplant or pregnancy.

Why is "Chronic graft arteriopathy from repeated low-grade injury" not the answer?

Chronic rejection develops over months to years with vascular intimal thickening.

Why is "Donor T cells attacking recipient tissues" not the answer?

Donor T cells attacking the recipient describe graft-versus-host disease, not graft rejection.

Why is "Donor-specific cytotoxic T cells attacking graft parenchyma over weeks" not the answer?

T-cell mediated attack is the mechanism of acute cellular rejection, over days to weeks.

What concept does this question test?

It tests Immunology in Microbiology. Antibodies bind donor endothelium, activate complement and cause thrombosis and necrosis. A negative cross-match prevents it.

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?

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.