Paracoccidioidomycosis (PCM) is a deep mycosis caused by Paracoccidioides brasiliensis, with high incidence in Brazil. In order to examine the immune response in lesional tissue from patients with PCM, we analyzed cytokines as well as the phenotype of the cell infiltrate. Paraffin-embedded tissue from the oral mucosa of eight patients with the localized adult form (AF) of PCM and from the lymph nodes of 10 patients with the juvenile form (JF) of PCM was analyzed by immunohistochemistry to detect tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), transforming growth factor-β (TGF-β) and interleukin-10 (IL-10). Most of the inflammatory cells in the lymph nodes were CD68+ (macrophages, epithelioid and giant cells), while a mixed infiltrate with macrophages, plasma cells and neutrophils was detected in the oral mucosa. TNF-α as well as iNOS expression was similar in lymph nodes and oral mucosa, whereas TGF-β and IL-10 were observed in a larger number of macrophages, epithelioid and giant cells in the lymph nodes, where numerous yeast cells were visualized. The higher expression of anti-inflammatory cytokines (IL-10 and TGF-β) in lesions of patients with the JF of PCM (lymph nodes) may represent a mechanism by which the fungus evades the host immune response, contributing to a more severe and disseminated form of the disease. © 2003 Elsevier Science Ltd. All rights reserved.215234241Franco, M., Montenegro, M.R., Mendes, R.P., Marques, S.A., Dillon, N.L., Mota, N.G.S., Paracoccidioidomycosis: A recently proposed classification of its clinical forms (1987) Rev Soc Bras Med Trop, 20, pp. 129-132Del Negro, G., Lacaz, C.S., Zamith, V.A., Siqueira, A.M., General clinical aspects: Polar forms of paracoccidioidomycosis, the disease in childhood (1994) Paracoccidioidomycosis, pp. 225-232. , M. Franco, C.S. 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