In fact, M. tuberculosis infection of IL-13-overexpressing (IL-13tg) mice results in lesions strongly resembling the pathology of human TB: central necrosis with a strict stratification of a fibrous capsule that separates the necrotizing granuloma from the adjoining tissue, foamy macrophages, found adjacent to the fibrous rim within the necrotic core, and dispersed multinucleated giant cells (18, 24, 25). This evidence concerns the gene IL13 and tuberculosis.