Blood and immunity: thymic selection: 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.

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Physiology · Blood and immunity: thymic selection

Sample item

During maturation in the thymus, a developing T cell whose receptor binds a self peptide-MHC complex with very high affinity is most likely to undergo which fate?

ADeath by neglectBSurvival and export to the peripheryCDifferentiation into a memory cellDClonal deletion by apoptosis

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

The answer and the reasoning

D. Clonal deletion by apoptosis

Thymocytes undergo positive selection, which rescues cells whose receptors recognise self MHC with low-to-moderate affinity, and negative selection, which deletes cells that bind self peptide-MHC strongly. Cells that cannot bind MHC at all die by neglect. Negative selection, aided by AIRE in the medulla, is a main mechanism of central tolerance.

Option by option

A. Death by neglect
Death by neglect affects cells that fail to recognise self MHC at all, not those that bind it strongly.
B. Survival and export to the periphery
Survival and export is the fate of cells with moderate affinity for self MHC.
C. Differentiation into a memory cell
Memory cell formation follows antigen encounter in the periphery and does not happen in the thymus.
D. Clonal deletion by apoptosis (correct)
Correct. High-affinity self-reactive cells are deleted by apoptosis.

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 D, Clonal deletion by apoptosis. Thymocytes undergo positive selection, which rescues cells whose receptors recognise self MHC with low-to-moderate affinity, and negative selection, which deletes cells that bind self peptide-MHC strongly.

Why is "Death by neglect" not the answer?

Death by neglect affects cells that fail to recognise self MHC at all, not those that bind it strongly.

Why is "Survival and export to the periphery" not the answer?

Survival and export is the fate of cells with moderate affinity for self MHC.

Why is "Differentiation into a memory cell" not the answer?

Memory cell formation follows antigen encounter in the periphery and does not happen in the thymus.

What concept does this question test?

It tests Blood and immunity: thymic selection in Physiology. Cells that cannot bind MHC at all die by neglect. Negative selection, aided by AIRE in the medulla, is a main mechanism of central tolerance.

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: thymic selection?

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.