Immunology: anti-TNF therapy and tuberculosis: 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: anti-TNF therapy and tuberculosis

Sample item

A 45-year-old man with rheumatoid arthritis, who had a strongly positive tuberculin test years ago, starts infliximab. Four months later he has fever, weight loss and an upper lobe cavity. Which immunological effect of the drug best explains this?

ALoss of TNF-alpha dependent granuloma maintenance, releasing latent bacilliBInhibition of complement-mediated opsonisation of bacilliCBlockade of IL-4 driven antibody class switchingDDepletion of CD8 T cells that kill infected macrophages

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

The answer and the reasoning

A. Loss of TNF-alpha dependent granuloma maintenance, releasing latent bacilli

TNF-alpha is needed to form and maintain the granuloma that walls off latent Mycobacterium tuberculosis. Anti-TNF drugs such as infliximab can break this containment, so latent infection should be screened for and treated before starting them.

Option by option

A. Loss of TNF-alpha dependent granuloma maintenance, releasing latent bacilli (correct)
Correct. Without TNF-alpha the granuloma disintegrates and latent tuberculosis reactivates.
B. Inhibition of complement-mediated opsonisation of bacilli
Opsonisation by complement is not the mechanism affected by TNF blockade.
C. Blockade of IL-4 driven antibody class switching
IL-4 and class switching are not the pathway restraining mycobacteria.
D. Depletion of CD8 T cells that kill infected macrophages
Infliximab does not deplete CD8 cells as its main effect.

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 Microbiology question

What is the answer to this Microbiology question?

The best answer is A, Loss of TNF-alpha dependent granuloma maintenance, releasing latent bacilli. TNF-alpha is needed to form and maintain the granuloma that walls off latent Mycobacterium tuberculosis.

Why is "Inhibition of complement-mediated opsonisation of bacilli" not the answer?

Opsonisation by complement is not the mechanism affected by TNF blockade.

Why is "Blockade of IL-4 driven antibody class switching" not the answer?

IL-4 and class switching are not the pathway restraining mycobacteria.

Why is "Depletion of CD8 T cells that kill infected macrophages" not the answer?

Infliximab does not deplete CD8 cells as its main effect.

What concept does this question test?

It tests Immunology: anti-TNF therapy and tuberculosis in Microbiology. Anti-TNF drugs such as infliximab can break this containment, so latent infection should be screened for and treated 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 Immunology: anti-TNF therapy and tuberculosis?

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.