Immunopathology: granuloma and TNF: 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 · Immunopathology: granuloma and TNF

Sample item

A 48-year-old woman with rheumatoid arthritis begins infliximab. Six months later she develops fever, weight loss and miliary shadows on chest radiograph, and biopsy shows poorly formed granulomas with many bacilli. What explains the reactivation of tuberculosis?

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

The answer and the reasoning

B. Neutralised TNF-alpha, which is needed to maintain granuloma integrity and macrophage activation

Granulomas arise when CD4+ Th1 cells secrete IFN-gamma that activates macrophages, and TNF-alpha made by macrophages helps recruit cells and maintain the granuloma wall. TNF blockers such as infliximab disrupt granulomas and cause latent tuberculosis to reactivate, so screening for latent TB is required before starting them.

Option by option

  • A. Depletion of B cells with loss of protective antibody

    B-cell depletion describes rituximab, and antibody is not the main defence against intracellular mycobacteria.

  • B. Neutralised TNF-alpha, which is needed to maintain granuloma integrity and macrophage activation (correct)

    Correct. TNF blockade breaks down the structure that contains the bacilli.

  • C. Inhibition of complement activation by the drug

    Infliximab acts on TNF and not on complement, which is not the main control of mycobacteria.

  • D. Complete loss of IFN-gamma gene expression

    The drug neutralises TNF; it does not delete IFN-gamma genes.

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 B, Neutralised TNF-alpha, which is needed to maintain granuloma integrity and macrophage activation. Granulomas arise when CD4+ Th1 cells secrete IFN-gamma that activates macrophages, and TNF-alpha made by macrophages helps recruit cells and maintain the granuloma wall.

Why is "Depletion of B cells with loss of protective antibody" not the answer?

B-cell depletion describes rituximab, and antibody is not the main defence against intracellular mycobacteria.

Why is "Inhibition of complement activation by the drug" not the answer?

Infliximab acts on TNF and not on complement, which is not the main control of mycobacteria.

Why is "Complete loss of IFN-gamma gene expression" not the answer?

The drug neutralises TNF; it does not delete IFN-gamma genes.

What concept does this question test?

It tests Immunopathology: granuloma and TNF in Pathology. TNF blockers such as infliximab disrupt granulomas and cause latent tuberculosis to reactivate, so screening for latent TB is required before starting them.

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 Immunopathology: granuloma and TNF?

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.