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.
Com o objetivo de padronizar modelo experimental de imunossupressão foram selecionados dois lotes de 50 camundongos impúberes, cada um dividido em grupos de 10, e submetidos a ação de dexametasona. O ...estudo foi dividido em dois experimentos. No primeiro experimento foi utilizado o primeiro lote de animais e foram estabelecidas as condições para obtenção de modelo de imunossupressão em camundongos mediante administração de dexametasona diluída na água de consumo e ingerida ad libitum pelos animais. Entre os critérios utilizados para avaliar a vigência de imunossupressão são realçados: a ocorrência de eriçamento de pelos, leucopenia por diminuição do número de linfócitos e hipotrofia do baço comparativamente aos controles, com hipoplasia intensa de todas as estruturas linfóides. No segundo experimento foi empregado o segundo lote de animais e foi estudado o comportamento do modelo experimental estabelecido. Os animais receberam, por via intraperitonial, número aproximado delO6 leveduras com os caracteres morfológicos do Cryptococcus neoformans, provenientes de culturas de cepas patogênicas ao homem e isoladas do líquido cefalorraqueano de pacientes com neurocriptococose. Apesar de haverem sido identificadas leveduras em cortes histológicos de pulmão, fígado e baço em todos os camundongos inoculados, somente ocorreu o óbito naqueles em que havia acometimento do sistema nervoso central pela levedura (aproximadamente 50% dos animais). A discussão dos resultados obtidos e seu significado inclui considerações sobre o possível papel desempenhado pela função barreira hêmato-encefálica no evento constatado.
In order to accomplish a model for immunossupression 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 immunossupression 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 immunossupression 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 immunossupression were submitted to intraperitonial innoculation of near 10e 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 innoculated, only those with central nervous system involvement (near by an half of all) died. The discussion includes considerations about the role of the blood-brain barrier function in the findings registered.
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