Immunology: aluminium adjuvant: 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: aluminium adjuvant

Sample item

Tetanus toxoid is adsorbed onto aluminium hydroxide before injection. What is the main benefit of the aluminium salt?

AIt converts the toxoid into a live attenuated antigenBIt forms a depot and enhances antigen uptake by antigen-presenting cellsCIt directly links the toxoid to a carrier proteinDIt permanently blocks the toxoid from being degraded

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

The answer and the reasoning

B. It forms a depot and enhances antigen uptake by antigen-presenting cells

Aluminium salts are adjuvants. They retain antigen at the injection site, which prolongs exposure, they improve uptake by dendritic cells and they promote innate inflammatory signalling, increasing antibody responses with fewer doses. Adjuvants do not change the nature of the antigen.

Option by option

A. It converts the toxoid into a live attenuated antigen
Adjuvants cannot convert an inactivated antigen into a live one.
B. It forms a depot and enhances antigen uptake by antigen-presenting cells (correct)
Correct. A depot effect and improved uptake by antigen-presenting cells boost the immune response.
C. It directly links the toxoid to a carrier protein
Carrier conjugation is a chemical linking of polysaccharide to protein, not the role of an aluminium salt.
D. It permanently blocks the toxoid from being degraded
Antigen is still degraded and processed; the adjuvant slows release.

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 B, It forms a depot and enhances antigen uptake by antigen-presenting cells. Aluminium salts are adjuvants.

Why is "It converts the toxoid into a live attenuated antigen" not the answer?

Adjuvants cannot convert an inactivated antigen into a live one.

Why is "It directly links the toxoid to a carrier protein" not the answer?

Carrier conjugation is a chemical linking of polysaccharide to protein, not the role of an aluminium salt.

Why is "It permanently blocks the toxoid from being degraded" not the answer?

Antigen is still degraded and processed; the adjuvant slows release.

What concept does this question test?

It tests Immunology: aluminium adjuvant in Microbiology. They retain antigen at the injection site, which prolongs exposure, they improve uptake by dendritic cells and they promote innate inflammatory signalling, increasing antibody responses with fewer doses. Adjuvants do not change the nature of the antigen.

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: aluminium adjuvant?

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.