Autoimmunity: type III hypersensitivity: 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 · Autoimmunity: type III hypersensitivity

Sample item

Serum sickness after foreign protein exposure is primarily mediated by which mechanism?

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

The answer and the reasoning

A. Immune-complex deposition

Serum sickness is a type III hypersensitivity reaction in which circulating immune complexes deposit in tissues and activate complement, causing fever, rash, arthralgia, and vasculitis.

Option by option

  • A. Immune-complex deposition (correct)

    Correct. Deposited antigen-antibody complexes drive type III injury.

  • B. Direct toxin-mediated necrosis

    Direct toxins are not immune-complex disease.

  • C. Cytotoxic T-cell killing

    Cytotoxic T-cell reactions are type IV.

  • D. IgE-mediated mast-cell degranulation

    IgE-mediated reactions are type I.

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 A, Immune-complex deposition. Serum sickness is a type III hypersensitivity reaction in which circulating immune complexes deposit in tissues and activate complement, causing fever, rash, arthralgia, and vasculitis.

Why is "Direct toxin-mediated necrosis" not the answer?

Direct toxins are not immune-complex disease.

Why is "Cytotoxic T-cell killing" not the answer?

Cytotoxic T-cell reactions are type IV.

Why is "IgE-mediated mast-cell degranulation" not the answer?

IgE-mediated reactions are type I.

What concept does this question test?

It tests Autoimmunity: type III hypersensitivity in Pathology. The correct option holds because: Correct. Deposited antigen-antibody complexes drive type III injury.

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 Autoimmunity: type III hypersensitivity?

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.