Which cells are primarily responsible for granuloma formation in tuberculosis?

• A. Neutrophils and eosinophils predominate in granulomas.
• B. Epithelial cells and eosinophils form granulomas.
• C. Activated macrophages (epithelioid cells) with T lymphocytes forming granulomas and Langhans giant cells.
• D. B cells and plasma cells form granulomas.

Answer: (C)

Granuloma formation in tuberculosis is driven by a cell-mediated immune response in which macrophages are activated and organize into a structured aggregate with T lymphocytes. The key players are activated macrophages that become epithelioid cells, often fusing to form Langhans-type giant cells, all surrounded by a ring of T cells. The Th1 response releases IFN-γ to keep macrophages in an activated state, promoting the collection of these epithelioid cells and giant cells into the granulomatous core, which may show caseous necrosis in TB. Neutrophils and eosinophils are not the main constituents of the granuloma, and B cells/plasma cells are not the primary organizing cells in this context.