Epithelial granuloma is caused by- (PGI, Dec, 2012)
a. Granulomatous inflammation is characterized by presence of epithelioid cells. These epithelioid cells are actually activated macrophages.
b. The immune granulomas are formed when infection occurs with microbes which are capable of inducing cell mediated response. In these cases i.e., type IV Hypersensitivity T-helper cells produces IL-2 which activates other T cells and macrophages, the activated macrophages in turn form epithelioid cells and help in granuloma formation.