In granulomatous inflammation (e.g., tuberculosis), the central area of caseous necrosis is surrounded by epithelioid macrophages and Langhans giant cells. What drives the formation of epithelioid macrophages?

• A IL-4 and IL-13 from Th2 cells causing alternative macrophage activation
• B TNF-alpha from NK cells inducing macrophage fusion
• C IFN-gamma from CD4+ Th1 cells activating macrophages to epithelioid form ✓
• D IL-17 from Th17 cells recruiting and differentiating macrophages

Explanation

Granuloma formation requires CD4+ Th1 lymphocytes secreting IFN-gamma, which activates macrophages to differentiate into epithelioid cells and fuse into multinucleated giant cells. TNF-alpha (from macrophages themselves) is critical for granuloma maintenance. IL-4/IL-13 drive alternative (M2) macrophage activation, promoting fibrosis, not granuloma formation.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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