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  • 1
    ISSN: 1600-065X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary:  T-helper 2 (Th2) cell responses play a critical role in protection against helminth infections. In the case of Schistosoma mansoni, an important helminth parasite of man, data from a mouse model of human disease have shown that Th2 responses are essential to allow host survival. In this infection, parasite eggs are the primary stimulus for Th2 response development. Recent work has shown that egg molecules exert multiple levels of control over the development of host interferon-γ-associated inflammatory responses. Soluble egg antigen inhibits the ability of dendritic cells to make interleukin-12 and induces Th2-polarized adaptive immune responses that in combination with regulatory T-cell responses effectively limit Th1 response development. In this article, we discuss the factors influencing Th2 response polarization during infection with S. mansoni.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0832
    Keywords: Cryptococcus neoformans ; macrophages ; T suppressor cells ; phagocytosis ; antigen presentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The influence of lymphocytes on the modulation of macrophage functions in altered immune states induced by Cryptococcus neoformans infection in rats has been investigated. In this report we observed a decrease of ‘in vitro’ phagocytic activity by peritoneal cells (PC) from rats that received T suppressor cells induced by cryptococcal infection, against both the same microorganism that stimulated this suppressor population (p〈0.05) and another non-pathogenic primary yeast (Candida tropicalis), (p〈0.02). The microbicide function of the PC from these animals present a significant decrease in challenge by C. tropicalis (p〈0.002) when compared with PC from animals transferred with T normal cells. The transference of T suppressor cells induced by cryptococcal infection in animals immunized with human serum albumin-complete Freund's adjuvant (HSA-CFA) produces a significant alteration of the phagocytosis to HSA-human red cells (HSA-HRC) when compared with the phagocytosis observed in animals that received T normal cells or the phagocytosis of normal animals (p〈0.001). We could also observe that the DTH to HSA studied during 30 days was negative in rats transferred with PC sensitizated with HSA and treated with suppressor T cells, when compared with the DTH response of animals transferred with PC-HSA cocultured with normal cells (p〈0.05 21st day). The data presented in this paper illustrated that following infection of rats with C. neoformans there is a change in some population of accessory cells behavior reflected by the modification of several functions, such as phagocytosis, lytic activity and antigen presentation.
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  • 3
    ISSN: 1573-0832
    Keywords: Cryptococcus neoformańs ; suppressor cells ; thymus ; thymic index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The presence of the microorganism, cortical hyperplasia and germinal centers was detected in the thymus of rats infected with 107 viable Cryptococcus neoformans cells and immunized at 7 days afterwards with 2.5 mg (0.1 ml) of human serum albumin (HSA) incorporated to complete Freund's adjuvant (CFA) (Group 2). There was no modification of the glandular structure in the thymus of the animals only immunized with HSA-CFA (Group 1). The weight of the thymus of group 2, animals infected and immunized, was increased compared with the weight of the thymus of group 1 animals, this became evident by the increase of the thymic index (TI) (p 〈0.005). This rate was obtained calculating the thymus weight/total body weight ratio × 1000. Thymic cells (107 cells in 1 ml) obtained from both groups of animals were transferred to normal syngeneic rats of the same sex. The recipient rats were immunized with HSA-CFA 24 h later and 14 days after the transference, the response of delayed-type hypersensitivity (DTH) was studied in them. It could be observed that the thymic cells coming from group 2 animals were capable of suppressing significatively the afferent pathway of the DTH response to HSA when compared with the response of the animals that received cells coming from group 1 rats (p〈0.0001).
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  • 4
    ISSN: 1573-0832
    Keywords: Cryptococcus neoformans ; Indomethacin ; Macrophages ; MHC Class II ; T-suppressor cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract When the I-A and I-E expressions were assessed in peritoneal macrophages fromCryptococcus neoformans infected animals, a significant decrease in the former was observed when compared with normal macrophages (p〈0.001) whereas a significant increase in the I-E expression was observed when compared with controls (p〈0.005). On the other hand, when studying the in vitro action of Ts cells on the macrophages, it was observed that the I-A expression was significantly reduced in macrophages upon contact with Ts cells. Similar results were obtained when Ts cells were replaced by a soluble factor. In contrast, the I-E expression was significantly increased by in vitro action of the Ts cell or its soluble factor. Indomethacin partially restored I-A and I-E expression in the macrophages to control levels.
    Type of Medium: Electronic Resource
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