Murine Macrophages Cultured with IL-4 Acquire a Phenotype Similar to That of Epithelioid Cells from Granulomatous Inflammation

Byline: Ivone Martins Cipriano (1), Mario Mariano (1), Edna Freymuller (2), Celia Regina Whitaker Carneiro (1) Keywords: epithelioid cells; granuloma; macrophages; IL-4; GM-CSF Abstract: Epithelioid cells (ECs) found in granulomas are thought to derive from mononuclear phagocytes. Although GM-CSF and/or IL-4 are known to promote cell differentiation their role in the development of ECs has never been demonstrated. Here we showed that mouse macrophages treated exclusively with recombinant IL-4 (rIL-4) differentiate into epithelioid-like cells. Macrophages cultivated with rIL-4 presented a fried-egg shape, and ultrastructural studies revealed membrane interdigitations, cytoplasmic vesicles, prominent Golgi complex, and rough endoplasmic reticulum. Compared with controls, rIL-4 treated cells displayed increased expression of MHC class II molecules and of Migration Inhibitory Factor-Related Protein-14. Whereas mannose receptor-mediated phagocytosis was increased, FcI3-receptor mediated phagocytosis and the production of nitric oxide were decreased in treated cultures. All these features overlap those reported for ECs from granulomatous lesions. In conclusion, treatment of mouse peritoneal macrophages with rIL-4 drives their in vitro differentiation to an epithelioid phenotype and provides a tool to investigate the biology of ECs. Author Affiliation: (1) Department of Microbiology, Immunology and Parasitology, Federal University of Sao Paulo, Sao Paulo, Brazil (2) Electron Microscopy Center, Federal University of Sao Paulo, Sao Paulo, Brazil Article History: Registration Date: 20/10/2004