Immunology: leukocyte adhesion deficiency: 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: leukocyte adhesion deficiency

Sample item

A 2-month-old infant had delayed umbilical cord separation at 5 weeks and now has omphalitis and a skin infection without pus. The neutrophil count is 40,000 per microlitre. Which defect is most likely?

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

The answer and the reasoning

B. Deficiency of CD18 beta-2 integrins on leukocytes

In leukocyte adhesion deficiency type 1, absent CD18 prevents firm adhesion and transmigration of neutrophils into tissues. Cells accumulate in blood, giving marked neutrophilia, while infected sites lack pus. Delayed cord separation beyond 3 weeks is the classic early clue.

Option by option

  • A. Deficiency of the oxidase that generates superoxide

    Oxidase deficiency allows migration but impairs killing, and cord separation is normal.

  • B. Deficiency of CD18 beta-2 integrins on leukocytes (correct)

    Correct. Without CD18 integrins, neutrophils cannot leave the vessels and pus does not form.

  • C. Failure of immunoglobulin class switching

    Class switching failure lowers IgG, IgA and IgE and does not cause neutrophilia.

  • D. Deficiency of the terminal complement components

    Terminal complement deficiency causes recurrent Neisseria infection.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is B, Deficiency of CD18 beta-2 integrins on leukocytes. In leukocyte adhesion deficiency type 1, absent CD18 prevents firm adhesion and transmigration of neutrophils into tissues.

Why is "Deficiency of the oxidase that generates superoxide" not the answer?

Oxidase deficiency allows migration but impairs killing, and cord separation is normal.

Why is "Failure of immunoglobulin class switching" not the answer?

Class switching failure lowers IgG, IgA and IgE and does not cause neutrophilia.

Why is "Deficiency of the terminal complement components" not the answer?

Terminal complement deficiency causes recurrent Neisseria infection.

What concept does this question test?

It tests Immunology: leukocyte adhesion deficiency in Microbiology. Cells accumulate in blood, giving marked neutrophilia, while infected sites lack pus. Delayed cord separation beyond 3 weeks is the classic early clue.

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 Immunology: leukocyte adhesion deficiency?

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.