Concanavalina-A aumenta a fagocitose e morte de Candida albicans por neutrófilos

Concanavalin A enhances phagocytosis and killing of Candida albicans by mice peritoneal neutrophils and macrophages

Artigo publicado na Revista FEMS Immunology & Medical Microbiology Volume 33, 3ª edição, páginas 201–208, Julho de 2002

Autoria: Wagner Loyola, Daniel Augusto Gaziri, Luis Carlos Jabur Gaziri e Ionice Felipe
Artigo completo: http://onlinelibrary.wiley.com/doi/10.1111/j.1574-695X.2002.tb00591.x/pdf

Neste estudo, testamos a hipótese de que uma única dose de concanavalina-A (Con-A) administrada por via intraperitoneal em camundongos, poderia estimular a migração de neutrófilos para a cavidade peritoneal e que estes fagócitos fossem eficientes na fagocitose e destruição de Candida albicans. Assim, o tratamento com Con-A (0,25 mg/ PBS) foi feito por via intraperitoneal e após 6hs o patógeno foi inoculado em PBS na concentração de (10⁸) na cavidade peritoneal. Após 1 h o exudato peritoneal foi analisado com laranja de acridina em microcópio de fluorescência. Verificou-se morte de C. albicans nos fagolisossomas e no meio extracelular e quando feito o plaqueamento em meio Sabouraud-dextrose observou-se redução de 80% das unidades formadoras de colônia (UFC). Quando a catalase foi inoculada junto com C. albicans, um maior número de leveduras e tubos germinativos vivos foram observados, sugerindo que sem o substrato de peróxido de hidrogênio, a mieloperoxidase de neutrófilos deixou de agir. Por outro lado, os fagócitos do grupo controle tratados com PBS (95% de macrófagos) foram capazes de matar somente 40% deste patógeno. Concluimos que a Con-A é um imunomodulador efetivo para atrair neutrófilos para a cavidade peritoneal os quais são eficientes para matar C. albicans.

Apoio financeiro: CNPq, CPG/UEL.

Abstract

In this study we tested the hypothesis that after administration of a single intraperitoneal dose of concanavalin A (Con-A) to mice, the proportion of neutrophils and macrophages in the peritoneal exudate and their phagocytic and candidacidal activities should change with time. The number of neutrophils in the peritoneal exudate was greatly increased 6 h after administration of Con-A, and those cells were able to kill both intracellular and extracellular yeast and germ tube forms of Candida albicans. Addition of catalase to the culture medium reduced the killing of C. albicans, suggesting that the candidacidal activity depended on the myeloperoxidase system. The survival of mice pretreated with Con-A and submitted to an inoculum of C. albicans 6 h afterwards was twice higher than that of controls, which suggests that neutrophils were able to clear the experimental infection. One day after the treatment, the population of neutrophils in the exudate was about 45%, but after 2 days it was reduced to only 5% and the candidacidal activity was also reduced. After 4 days the exudate contained over 95% of macrophages, the candidacidal activity reached a maximum, and the phagocytosis mediated by both complement receptors and mannose receptors was increased. Uptake of FITC^mannose^BSA by macrophages was maximal on about the 4th day and was inhibited by mannan, suggesting that treatment with Con-A increased the activity of mannose receptors. These results support the hypothesis that activation of cellular immunity by Con-A occurred in two phases, one dominated by neutrophils, and the other by macrophages expressing increased activity of mannose receptors.

2002 Federation of European Microbiological Societies. Published
by Elsevier Science B.V. All rights reserved.