DOSE-EFFECT OF ORAL SACCHAROMYCES-BOULARDII TREATMENTS ON MORBIDITY AND MORTALITY IN IMMUNOSUPPRESSED MICE

Survival, weight loss, translocation and histological alterations in t he terminal ileum, liver and spleen were studied in mice simultaneousl y immunosuppressed with cyclophosphamide and treated or not with Sacch aromyces boulardii until the death of all animals. The animals were di vided into five groups: C1 (not immunosuppressed, not treated); C2 (im munosuppressed, not treated); B1 (immunosuppressed, treated with S. bo ulardii 10.0 mg); B2 (immunosuppressed, treated with S. boulardii 1.0 mg) and B3 (immunosuppressed, treated with S. boulardii 0.1 mg). Survi val was higher in group B3 than in the other immunosuppressed groups. Weight loss was observed for all groups except C1. By day 7, some anim als from each group were killed by ether inhalation for the determinat ion of bacterial translocation and histopathological examination. Bact erial translocation to the liver was lower in groups C1 and B3 than in the other groups. The highest translocation to the liver and spleen w as observed in group B1. Low S. boulardii translocation was observed i n some animals, principally to the mesenteric lymph nodes. Histopathol ogical examination showed a decrease in epithelial cell turnover with villus length reduction and loss of brush borders in group C2. Relativ e protection against these alterations was obtained when the animals w ere treated with the yeast, independently of the dose. Higher expressi on of the lymphoid component was also noted in the ileal lamina propri a, liver and spleen of mice treated with the yeast, together with acti vation of the reticulo-endothelial system, when compared with group C2 where lymphocyte depletion was observed. This study suggests a relati ve protection of immunosuppressed animals by treatment with S. boulard ii, but this phenomenon was inversely proportional to the yeast dose.