Blood and immunity: immune complex clearance: practice question

A Physiology 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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Physiology · Blood and immunity: immune complex clearance

Sample item

A patient with systemic lupus erythematosus has low C3 and C4 with high anti-dsDNA titres, and immune complexes lodge in the glomeruli. Which immune mechanism produces the tissue injury?

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

The answer and the reasoning

D. Complement activation and neutrophil recruitment by deposited immune complexes

Lupus nephritis is a type III hypersensitivity. Immune complexes deposit in the glomerular basement membrane, activate the classical complement pathway and attract neutrophils, which release enzymes and cause injury. Complement consumption explains the low C3 and C4.

Option by option

  • A. IgE-triggered release of preformed mast cell mediators

    IgE and mast cell mediators describe type I hypersensitivity.

  • B. Antibody stimulation of a cell surface receptor

    Antibody stimulation of a receptor, as in Graves disease, is a stimulatory variant of type II.

  • C. Direct cytolysis by sensitised CD8 T cells

    Direct CD8 T cell killing describes type IV mechanisms.

  • D. Complement activation and neutrophil recruitment by deposited immune complexes (correct)

    Correct. Immune complex deposition activates complement and attracts neutrophils.

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 Physiology question

What is the answer to this Physiology question?

The best answer is D, Complement activation and neutrophil recruitment by deposited immune complexes. Lupus nephritis is a type III hypersensitivity.

Why is "IgE-triggered release of preformed mast cell mediators" not the answer?

IgE and mast cell mediators describe type I hypersensitivity.

Why is "Antibody stimulation of a cell surface receptor" not the answer?

Antibody stimulation of a receptor, as in Graves disease, is a stimulatory variant of type II.

Why is "Direct cytolysis by sensitised CD8 T cells" not the answer?

Direct CD8 T cell killing describes type IV mechanisms.

What concept does this question test?

It tests Blood and immunity: immune complex clearance in Physiology. Immune complexes deposit in the glomerular basement membrane, activate the classical complement pathway and attract neutrophils, which release enzymes and cause injury. Complement consumption explains the low C3 and C4.

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 Blood and immunity: immune complex clearance?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.