Mycopathologia 138: 65–69, 1997. 65 c 1997 Kluwer Academic Publishers. Printed in the Netherlands. Monocyte adherence to Paracoccidioides brasiliensis , zymosan-C3b and erythrocyte-hemolysin in patients with paracoccidioidomycosis M.A. Shikanai-Yasuda 12 , C.M. Assis 3 , K.M. Takeda 1 , Nair Tamashiro 1 & J.P. Bueno 1 Laborat´ orio de Investigac ¸˜ ao M´ edica em Imunologia (LIM 48) - Hospital das Cl´ inicas; 2 Departamento de Doenc ¸as Infecciosas e Parasit´ arias – Faculdade de Medicina da USP e 3 Instituto Adolfo Lutz, S ˜ ao Paulo, Brasil. (Received 26 April 1996; accepted in final form 21 July 1997) Abstract Independent and dependent (C3b/Fc receptors) opsonic adherence ability of monocytes from thirty-three patients with acute or chronic paracoccidioidomycosis and from 13 healthy individuals were studied in the presence of Paracoccidioides brasiliensis (Pb), Paracoccidioides brasiliensis opsonized by patient’s serum (PbPS) or normal serum (PbNS), zymosan opsonized by fresh sera from healthy donors (ZyNS) and erythrocytes opsonized by hemolysin (EA). Statistically significant differences concerning the percentage of adhered monocytes to PbPS (number of adhered monocytes/total number of monocytes) were detected between control and chronic (active and inactive) groups. Significant differences in relationship to the mean number of PbPS (number of fungi in monocytes/total number of monocytes) were also observed between control and chronic active mycosis. Present data suggest that patients with chronic disease have more ability in the first step of phagocytic activity, considered as the main effector mechanism to control the dissemination and severity of paracoccidiodomycosis. Key words: Monocytes, Phagocytosis, Paracoccidioides brasiliensis, paracoccidioidomycosis. Introduction Paracoccidioidomycosis is a systemic granulomatous mycosis involving mainly the phagocytic mononuclear system in young patients and most commonly the lungs in adult patients. Deficiencies of in vitro and in vivo cellular immune response have been associated with human severe disease [1]. Although macrophage activation has been estab- lished as the most important host effector response to control the infection [2,3], the initial steps of fungus – human interaction have not been studied. Many ques- tions are not well understood such as the role of alveolar macrophages as the initial defense mechanism, the low frequency of pulmonary symptoms in acute disease as well as the role of monocytes in the dissemination of fungi in the acute or chronic form of the disease. The aim of this paper is to analyse the opsonic adherence ability of monocytes from patients with paracoccidioidomycosis and their adherence ability through C3b and to Fc receptors. Patients, Material and Methods Patients. Thirty-three patients with paracoccid- ioidomycosis comprise subgroups 1, 2 and 3 with, respectively, 13 patients with the chronic, 9 with the acute form of the disease and 11 patients with clinically inactive chronic disease. The diagnosis of this myco- sis was established by mycological and/or histopatho- logical and/or serological methods (immunodiffusion and contraimmunoelectrophoresis tests with Paracoc- cidioides brasiliensis antigens). The disease is con- sidered clinically inactive when symptoms and signs were absent and the titer of specific antibodies is low- er than 1/32 by contraimmunoelectrophoresis. Control subgroup (number 4) comprises 13 clinically healthy blood donors. Materials and Methods. Mononuclear cells were separated by density gradient centrifugation and placed on coverslips in Leighton tubes. Monocytes were selected by adherence to coverslips. After washing the