Question:medium
Which cytokine activates macrophages?
Which cytokine activates macrophages?
Show Hint
Which Th1/NK-cell cytokine drives classical (M1) macrophage activation?
Updated On: Jun 24, 2026
- IL-8
- IFN-gamma
- PAF
- Leukotriene B4
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Frame the answer around macrophage polarisation. The M1 (classical) phenotype is the killer, inflammatory state, whereas the M2 (alternative) phenotype, driven by IL-4 and IL-13, favours repair and produces IL-10 and TGF-beta.
Step 2: The signature signal that pushes macrophages into the aggressive M1 state is IFN-gamma, the hallmark cytokine of Th1 cells and NK cells. With microbial triggers it boosts oxygen radicals, nitric oxide and IL-12 secretion, sharpening killing power.
Step 3: Test each wrong choice against this. IL-8 simply calls in neutrophils. PAF acts on vessels and platelets. Leukotriene B4 is again a neutrophil chemoattractant. None of them flip the macrophage activation switch.
Step 4: The macrophage-activating cytokine is therefore IFN-gamma.
\[\boxed{\text{IFN-gamma}}\]
Step 2: The signature signal that pushes macrophages into the aggressive M1 state is IFN-gamma, the hallmark cytokine of Th1 cells and NK cells. With microbial triggers it boosts oxygen radicals, nitric oxide and IL-12 secretion, sharpening killing power.
Step 3: Test each wrong choice against this. IL-8 simply calls in neutrophils. PAF acts on vessels and platelets. Leukotriene B4 is again a neutrophil chemoattractant. None of them flip the macrophage activation switch.
Step 4: The macrophage-activating cytokine is therefore IFN-gamma.
\[\boxed{\text{IFN-gamma}}\]
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