LOCALIZATION OF EOSINOPHIL GRANULE MAJOR BASIC-PROTEIN IN PARACOCCIDIOIDOMYCOSIS LESIONS

Paracoccidioidomycosis is a chronic granulomatous disease caused by th e fungus Paracoccidioides brasiliensis. Although eosinophils have long been associated with the immune defense against helminths, the role o f eosinophils in the immune response to fungal diseases is not as well studied. The eosinophil granule major basic protein is toxic to helmi nths and mammalian cells in vitro, and its release has been used as a marker of eosinophil localization and degranulation. To determine whet her eosinophil infiltration and degranulation. as evidenced by the dep osition of major basic protein, occur in lesions of P, brasiliensis, w e used an immunofluorescence technique to localize the P. brasiliensis organisms and eosinophils and major basic protein. Initially, all tis sues were stained with polyclonal antibody to major basic protein; sub sequently. colocalization of major basic protein and P. brasiliensis b y double staining with mouse and rabbit antibodies, respectively, was performed. Nine biopsy tissues from seven patients were analyzed. All nine biopsies showed infiltration of intact eosinophils using both the monoclonal and the polyclonal anti-major basic protein antibodies, al ong with the presence of P, brasiliensis, Furthermore, using the polyc lonal anti major basic protein antibody, nine of nine tissues showed e xtracellular major basic protein deposition (granular or diffuse fluor escence staining outside of intact eosinophils). The double staining p rocedure using the anti-major basic protein monoclonal antibody showed extracellular deposition in five of eight biopsies, in these five bio psies, approximately 60% of the areas containing P. brasiliensis had e xtracellular major basic protein deposited on the organisms. These obs ervations support the hypothesis that the eosinophil, through toxic gr anule proteins such as major basic protein, participates in the pathop hysiology of paracoccidioidomycosis.