THE ROLE OF SOMATIC STRUCTURE OF THE FUNGUS PARACOCCIDIOIDES-BRASILIENSIS UPON B-CELL ACTIVATION IN EXPERIMENTAL PARACOCCIDIOIDOMYCOSIS

In this study, we report an increase of the number of antibody-secreti ng cells and the augmentation of antibody production against unrelated antigens in mice infected with the fungus P. brasiliensis, as well as in mice inoculated with cell wall preparation isolated from P. brasil iensis (CW). The immunomodulatory effect of the live fungus and the CW preparation was dose-dependent, and their actions were mainly restric ted to the i.v. or i.p. inoculation simultaneously with the sheep eryt hrocyte challenge by the i.v. route or restricted to i.p. inoculation of CW when bovine serum albumin (BSA) antigen was used. The dependence of antibody production on different routes of CW inoculation was corr elated with the number of antigen-specific B cells in the spleen as de termined by direct and reverse plaque-forming cell assays. The immuniz ation schedules using CW preparation caused a I,referential production of IgM and IgG3 antibodies. The results also showed that the hyperact ive: humoral immune response of mice induced by i.p. inoculation of CW was devoid of polyclonal B cell activation compared with the effects observed for the lipopolysaccharide (LPS)-treated groups. Paracoccidio ides brasiliensis CW components may have potent immunological properti es related to the non-specific B cell activation found in paracoccidio idomycosis.