[Neurocryptococosis and immunosuppression: experimental model in mice].

In order to accomplish a model for immunosuppression in experimental conditions two lots of 50 young mice were divided into groups of 10, and submitted to dexamethasone ingestion. Two experiments were considered in the study. In the first experiment conditions for immunosuppression were established in 50 mice, by per os supply of several concentrations of dexamethasone in the water given for normal daily intake ad libitum. Criteria of immunosuppression considered include: hair standing on end; leukopenia by decrease of lymphocyte population; spleen atrophy in relation to controls, with severe hypoplasy of all lymphoid structures. In the second experiment another lot of 50 mice in similar conditions established for the first experiment and concerning the immunosuppression were submitted to intraperitoneal inoculation of near 10(6) Cryptococcus neoformans. Culture suspensions of cryptococci isolated from cerebrospinal fluid samples of human neurocryptococcosis cases were used for this purpose. Although fungi could be recognized in lungs, liver and spleen from every mice inoculated, only those with central nervous system involvement (near by an half of all) died. The discussion included considerations about the role of the blood-brain barrier function in the findings registered.