Immune responses of IL-5 transgenic mice to parasites and aeroallergens

Eosinophils have long been thought to be effectors of immunity to helminth but have also been implicated in the pathogenesis of asthma. Patterns of cytokine production in the host may influence the pathogenesis of these diseases by regulating the activities of eosinophils and other components of the immune response. Mice which constitutively over-express IL-5 have profound and life-long eosinophilia in a restricted number of tissues. Although eosinophils from IL-5 transgenics are funtionally competent for a number of parameters considered to be important in inflammation, untreated animals are overtly normal and free of disease. In addition, the responses of these animals when exposed to aeroallergens and helminth present a number of apparent paradoxes. Eosinophil accumulation in tissue adjacent to major airways is rapid and extensive in transgenics exposed to the aeroallergen, but even after treatment with antigen over many months these mice show no evidence of respiratory distress or pathology. Helminth-infected IL-5 transgenics and their non-transgenic littermates develop similar inflammatory responses at mucosal sites and are comparable for a number of T cell and antibody responses, but they differ considerably in their ability to clear some parasite species. The life-cycle of Nippostrongylus brasilensis is significantly inhibited in IL-5 transgenics, but that of Toxocara canis is not. Our results suggest that eosinophilia and/or over-expression of IL-5 may actually impair host resistance to Schistosoma mansoni and Trichinella spiralis. The pathogenesis of diseases in which eosinophils are involved may therefore be more complex than previously thought.

Factores de crecimiento y diferenciación en varias cepas de leishmanias: desarrollo de medios de cultivo químicamente definidos / Growth factors and differentiations in several leishmania species: development of the culture medium chemically defined

Hemos desarrollado un medio de cultivo libre de proteinas y se contiene sales, glucosa, D-ribosa, 2-deoxyribosa, hemina, tricina, HEPES, 34 aminoácidos, 23 vitaminas, 6 nucleótidos y ácido tetrahidrofólico, donde 17 cepas de Leishmanias pertenecientes a 4 especies: brasiliensis, mexicana, donovani y garnhami crecen en forma continua a 26 grados C. Las distintas especies presentan una variabilidad muy grande en cuanto a requerimientos nutritivos se refiere, lo cual nos ha llevado a preparar medios minimos químicamente definidos para cada subespecie de Leishmania. La virulencia de los parasitos en estos medios se mantiene después de 30 pasajes en el medio definido. Los requimientos para la diferenciación en amastigotes también cambian según las especies de Leishmanias y varia en función de la temperatura del medio de cultivo así como del contenido proteico del mismo. Los péptidos trípticos obtenidos de la albúmina sérica bovina sustituyen al suero fetal bovino como factor de crecimiento entre 30-34 grados C