Immunity: leukocyte adhesion deficiency: 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 · Immunity: leukocyte adhesion deficiency

Sample item

A 3-month-old infant had delayed umbilical cord separation and now has recurrent skin infections without pus formation. Blood neutrophil count is very high. Which neutrophil step is defective?

APhagolysosome fusion through lysosomal trafficking regulatorBFirm adhesion to endothelium through beta-2 integrins (CD18)CGeneration of the oxidative burst by NADPH oxidaseDRolling along endothelium through sialyl Lewis X

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

The answer and the reasoning

B. Firm adhesion to endothelium through beta-2 integrins (CD18)

In leukocyte adhesion deficiency type 1, absent CD18 (beta-2 integrin) prevents firm adhesion and transmigration, so neutrophils accumulate in blood but cannot reach tissues. Features are delayed cord separation, neutrophilia, and infections without pus. Other neutrophil defects present differently.

Option by option

A. Phagolysosome fusion through lysosomal trafficking regulator
A lysosomal trafficking defect is Chediak-Higashi syndrome, with giant granules and albinism.
B. Firm adhesion to endothelium through beta-2 integrins (CD18) (correct)
Correct. Without beta-2 integrins, neutrophils cannot adhere firmly and exit the vessel.
C. Generation of the oxidative burst by NADPH oxidase
A defective oxidative burst causes chronic granulomatous disease, where pus and granulomas do form.
D. Rolling along endothelium through sialyl Lewis X
A defect in rolling ligands is seen in type 2 leukocyte adhesion deficiency, which has a Bombay phenotype and developmental delay.

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 B, Firm adhesion to endothelium through beta-2 integrins (CD18). In leukocyte adhesion deficiency type 1, absent CD18 (beta-2 integrin) prevents firm adhesion and transmigration, so neutrophils accumulate in blood but cannot reach tissues.

Why is "Phagolysosome fusion through lysosomal trafficking regulator" not the answer?

A lysosomal trafficking defect is Chediak-Higashi syndrome, with giant granules and albinism.

Why is "Generation of the oxidative burst by NADPH oxidase" not the answer?

A defective oxidative burst causes chronic granulomatous disease, where pus and granulomas do form.

Why is "Rolling along endothelium through sialyl Lewis X" not the answer?

A defect in rolling ligands is seen in type 2 leukocyte adhesion deficiency, which has a Bombay phenotype and developmental delay.

What concept does this question test?

It tests Immunity: leukocyte adhesion deficiency in Physiology. Features are delayed cord separation, neutrophilia, and infections without pus. Other neutrophil defects present differently.

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 Immunity: leukocyte adhesion deficiency?

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.