Immunology: mixed lymphocyte 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.

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Microbiology · Immunology: mixed lymphocyte reaction

Sample item

In a one-way mixed lymphocyte reaction used for assessing donor and recipient compatibility, the donor cells are treated with mitomycin C or irradiated. Why?

ATo kill the recipient's cellsBTo convert donor cells into B cellsCTo prevent donor cells from proliferating so that only recipient responder T cells are measuredDTo make donor cells present antigens more strongly

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

The answer and the reasoning

C. To prevent donor cells from proliferating so that only recipient responder T cells are measured

In the mixed lymphocyte reaction, recipient T cells proliferate in response to foreign MHC class II on donor cells, measured by thymidine incorporation. Treating donor cells prevents their own proliferation, so the measured response comes only from the recipient. This produces a one-way reaction.

Option by option

A. To kill the recipient's cells
The treatment is applied to the donor stimulator cells, and the recipient cells are the responders that need to stay viable.
B. To convert donor cells into B cells
Lymphocytes do not change lineage on exposure to mitomycin or radiation.
C. To prevent donor cells from proliferating so that only recipient responder T cells are measured (correct)
Correct. Treated stimulator cells cannot divide, so proliferation reflects the recipient's responding T cells.
D. To make donor cells present antigens more strongly
Irradiation does not enhance antigen presentation; it only prevents division.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is C, To prevent donor cells from proliferating so that only recipient responder T cells are measured. In the mixed lymphocyte reaction, recipient T cells proliferate in response to foreign MHC class II on donor cells, measured by thymidine incorporation.

Why is "To kill the recipient's cells" not the answer?

The treatment is applied to the donor stimulator cells, and the recipient cells are the responders that need to stay viable.

Why is "To convert donor cells into B cells" not the answer?

Lymphocytes do not change lineage on exposure to mitomycin or radiation.

Why is "To make donor cells present antigens more strongly" not the answer?

Irradiation does not enhance antigen presentation; it only prevents division.

What concept does this question test?

It tests Immunology: mixed lymphocyte reaction in Microbiology. Treating donor cells prevents their own proliferation, so the measured response comes only from the recipient. This produces a one-way reaction.

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: mixed lymphocyte 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.