Inflammation: leukocyte adhesion deficiency: practice question

A Pathology 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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Pathology · Inflammation: leukocyte adhesion deficiency

Sample item

A 3-week-old infant still has an unseparated umbilical stump with surrounding erythema. There is no pus at the site, yet the blood count shows a total leukocyte count of 45,000 per microlitre with marked neutrophilia. Which molecular defect is most likely?

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

The answer and the reasoning

A. Deficiency of the CD18 beta-2 integrin subunit on leukocytes

Leukocyte adhesion deficiency type 1 results from mutations in the CD18 subunit shared by LFA-1 and Mac-1. Neutrophils cannot adhere firmly to endothelium and so cannot leave the vessels, which produces a very high circulating count but no pus at the infected site. Delayed separation of the umbilical cord is the classic early sign.

Option by option

  • A. Deficiency of the CD18 beta-2 integrin subunit on leukocytes (correct)

    Correct. Loss of beta-2 integrins blocks firm adhesion and transmigration, so neutrophils accumulate in blood and not in tissue.

  • B. Defective lysosomal trafficking regulator protein

    A lysosomal trafficking regulator defect causes Chediak-Higashi syndrome with giant granules and partial albinism.

  • C. Deficiency of NADPH oxidase in phagocytes

    NADPH oxidase deficiency causes chronic granulomatous disease, where neutrophils reach the site but cannot kill catalase-positive organisms.

  • D. Absence of the C3 component of complement

    C3 deficiency causes recurrent severe pyogenic infections with pus formation, and does not delay cord separation.

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.

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Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is A, Deficiency of the CD18 beta-2 integrin subunit on leukocytes. Leukocyte adhesion deficiency type 1 results from mutations in the CD18 subunit shared by LFA-1 and Mac-1.

Why is "Defective lysosomal trafficking regulator protein" not the answer?

A lysosomal trafficking regulator defect causes Chediak-Higashi syndrome with giant granules and partial albinism.

Why is "Deficiency of NADPH oxidase in phagocytes" not the answer?

NADPH oxidase deficiency causes chronic granulomatous disease, where neutrophils reach the site but cannot kill catalase-positive organisms.

Why is "Absence of the C3 component of complement" not the answer?

C3 deficiency causes recurrent severe pyogenic infections with pus formation, and does not delay cord separation.

What concept does this question test?

It tests Inflammation: leukocyte adhesion deficiency in Pathology. Neutrophils cannot adhere firmly to endothelium and so cannot leave the vessels, which produces a very high circulating count but no pus at the infected site. Delayed separation of the umbilical cord is the classic early sign.

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 Inflammation: leukocyte adhesion deficiency?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.