Blood and immunity: neutrophil rolling: 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: neutrophil rolling

Sample item

In acute bacterial infection, circulating neutrophils first roll slowly along the wall of the post-capillary venule before they stick firmly and cross it. Which molecules mediate the initial rolling?

AChemokine receptors that bind interleukin-8 on endotheliumBPECAM-1 binding at endothelial intercellular junctionsCSelectins on endothelium binding sialylated carbohydrates on neutrophilsDIntegrins LFA-1 binding ICAM-1 on endothelium

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

The answer and the reasoning

C. Selectins on endothelium binding sialylated carbohydrates on neutrophils

Leucocyte emigration proceeds in stages: margination, rolling, firm adhesion, transmigration and chemotaxis. Rolling is a low-affinity interaction between endothelial E- and P-selectin and sialylated ligands on the leucocyte. Firm adhesion needs integrins and ICAM-1, and diapedesis uses PECAM-1.

Option by option

A. Chemokine receptors that bind interleukin-8 on endothelium
Chemokines such as interleukin-8 activate the integrins and guide migration, but they do not tether the rolling cell.
B. PECAM-1 binding at endothelial intercellular junctions
PECAM-1 is used when the cell squeezes between endothelial cells, after firm adhesion.
C. Selectins on endothelium binding sialylated carbohydrates on neutrophils (correct)
Correct. Selectin binding to sialylated ligands slows the cell and causes rolling.
D. Integrins LFA-1 binding ICAM-1 on endothelium
Integrin and ICAM-1 binding gives firm adhesion after chemokine activation, which is the next stage.

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 C, Selectins on endothelium binding sialylated carbohydrates on neutrophils. Leucocyte emigration proceeds in stages: margination, rolling, firm adhesion, transmigration and chemotaxis.

Why is "Chemokine receptors that bind interleukin-8 on endothelium" not the answer?

Chemokines such as interleukin-8 activate the integrins and guide migration, but they do not tether the rolling cell.

Why is "PECAM-1 binding at endothelial intercellular junctions" not the answer?

PECAM-1 is used when the cell squeezes between endothelial cells, after firm adhesion.

Why is "Integrins LFA-1 binding ICAM-1 on endothelium" not the answer?

Integrin and ICAM-1 binding gives firm adhesion after chemokine activation, which is the next stage.

What concept does this question test?

It tests Blood and immunity: neutrophil rolling in Physiology. Rolling is a low-affinity interaction between endothelial E- and P-selectin and sialylated ligands on the leucocyte. Firm adhesion needs integrins and ICAM-1, and diapedesis uses PECAM-1.

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 Blood and immunity: neutrophil rolling?

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.