Granuloma formation requires which cytokine signal from macrophages that drives differentiation of CD4+ T-helper cells into IFN-γ-producing Th1 cells to sustain macrophage activation?
- A IL-4
- B IL-12 ✓
- C IL-10
- D IL-13
Correct answer: B. IL-12
Explanation
IL-12 produced by macrophages and dendritic cells is the key cytokine driving naive CD4+ T-cell differentiation into Th1 cells. Th1 cells secrete IFN-γ, which activates macrophages to become epithelioid cells and fuse into giant cells — the cellular hallmarks of the granuloma. IL-4 and IL-13 drive Th2 differentiation; IL-10 is anti-inflammatory. Defects in IL-12 or IFN-γ signaling impair granuloma formation and predispose to mycobacterial infections.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.