Involvement of cell wall glucans in the genesis and persistence of the inflammatory reaction caused by the fungus Paracoccidioides brasiliensis.

Abstract

The role of cell wall polysaccharides in leucocyte recruitment and granuloma formation in paracoccidioidomycosis was investigated. The inflammatory cells recruitment to the peritoneal cavity in rats inoculated with cell wall fraction (CW-265 or F1-265) from an avirulent strain of Paracoccidioides brasiliensis (Pb265), was greater than that observed for the cell wall fraction (CW-HC or F1-HC) recovered from the virulent strain (PbHC). Moreover, the inoculation of F1-HC and F1-265 into the subcutaneous layer of mice resulted in the formation of nodular and not progressive granulomatous lesions. The size and mean time of evolution of these lesions was proportional to the degree of virulence of the sample from which they were derived. Analyses showed that both F1 fractions contained beta-glucan and chitin. Only beta-glucan was able to trigger attraction and concentric organization of polymorphonuclear neutrophils and macrophages at the inflammatory foci, and the difference in the concentration of this compound in the cell walls of PbHC and Pb265 could explain the inflammatory capacity exhibited by the two strains of P. brasiliensis.