Inflammation: macrophage polarisation: 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: macrophage polarisation

Sample item

In the late phase of a healing wound, macrophages exposed to IL-4 and IL-13 differ from those activated by interferon-gamma. Which property characterises the IL-4 and IL-13 stimulated macrophages?

AHigh production of nitric oxide and reactive oxygen speciesBSecretion of IL-12 and IL-23 to drive Th1 and Th17 responsesCStrong induction of inducible nitric oxide synthaseDSecretion of TGF-beta and growth factors promoting fibrosis and angiogenesis

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

The answer and the reasoning

D. Secretion of TGF-beta and growth factors promoting fibrosis and angiogenesis

Classically activated (M1) macrophages arise with interferon-gamma and microbial products, and kill microbes by nitric oxide, reactive oxygen species and lysosomal enzymes. Alternatively activated (M2) macrophages arise with IL-4 and IL-13 and are anti-inflammatory. They secrete TGF-beta, PDGF and VEGF, and promote repair, fibrosis and angiogenesis.

Option by option

A. High production of nitric oxide and reactive oxygen species
High nitric oxide and reactive oxygen species output is a feature of M1 macrophages.
B. Secretion of IL-12 and IL-23 to drive Th1 and Th17 responses
IL-12 and IL-23 secretion belongs to classically activated macrophages that drive Th1 and Th17 cells.
C. Strong induction of inducible nitric oxide synthase
Inducible nitric oxide synthase induction is typical of M1 and not of M2 macrophages.
D. Secretion of TGF-beta and growth factors promoting fibrosis and angiogenesis (correct)
Correct. M2 macrophages favour tissue repair through TGF-beta and other growth factors.

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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Secretion of TGF-beta and growth factors promoting fibrosis and angiogenesis. Classically activated (M1) macrophages arise with interferon-gamma and microbial products, and kill microbes by nitric oxide, reactive oxygen species and lysosomal enzymes.

Why is "High production of nitric oxide and reactive oxygen species" not the answer?

High nitric oxide and reactive oxygen species output is a feature of M1 macrophages.

Why is "Secretion of IL-12 and IL-23 to drive Th1 and Th17 responses" not the answer?

IL-12 and IL-23 secretion belongs to classically activated macrophages that drive Th1 and Th17 cells.

Why is "Strong induction of inducible nitric oxide synthase" not the answer?

Inducible nitric oxide synthase induction is typical of M1 and not of M2 macrophages.

What concept does this question test?

It tests Inflammation: macrophage polarisation in Pathology. Alternatively activated (M2) macrophages arise with IL-4 and IL-13 and are anti-inflammatory. They secrete TGF-beta, PDGF and VEGF, and promote repair, fibrosis and angiogenesis.

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 Inflammation: macrophage polarisation?

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.