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Complement resistance of Leishmania amazonensis promastigotes is independent of parasite proteases and lysis of sensitive forms is not due to natural antibodies in normal human serum
Braz. j. med. biol. res ; 29(12): 1633-40, Dec. 1996. ilus, graf
Artigo em Inglês | LILACS | ID: lil-188446
RESUMO
Leishmania amazonensis promastigotes cultivated in vitro differentiate from complement-sensitive to complement-resistant forms. In order to determine the possible involvement of parasite proteases in this process, L. amazonensis promastigotes were collected daily and their proteolytic enzyme patterns analyzed using polyacrylamide gels copolymerized with gelatin. Although promastigotes at different growth stages showed differences in protease patterns, these changes did not correlate with their susceptibility to complement. The major protease of promastigotes, gp63, was expressed at the same level throughout culture, regardless of the complement resistance of the promastigotes. Furthermore, inhibitors specific for the classes of proteases found in L. amazonensis promastigotes did not interfere with the complement-mediated killing of promastigotes. We also investigated the binding of natural antibodies to promastigotes at different stages of growth using ELISA. Although complement-sensitive promastigotes bound significantly more antibodies from fresh normal human serum than complement-resistant promastigotes, equivalent amounts of C3 were detected on their surfaces following complement activation. Moreover, serum depleted of anti-Leishmania antibodies was as efficient in killing promastigotes as the intact serum. These data suggest that the resistance of L. amazonensis to complement killing involves strategies other than that of the regulated expression endogenous proteases capable of inactivating complement components, or the differential ability to bind natural antibodies that might interfere with complement deposition on the parasite surface.
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Índice: LILACS (Américas) Assunto principal: Técnicas In Vitro / Leishmania mexicana / Proteínas do Sistema Complemento Tipo de estudo: Estudo diagnóstico Limite: Animais Idioma: Inglês Revista: Braz. j. med. biol. res Assunto da revista: Biologia / Medicina Ano de publicação: 1996 Tipo de documento: Artigo

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Índice: LILACS (Américas) Assunto principal: Técnicas In Vitro / Leishmania mexicana / Proteínas do Sistema Complemento Tipo de estudo: Estudo diagnóstico Limite: Animais Idioma: Inglês Revista: Braz. j. med. biol. res Assunto da revista: Biologia / Medicina Ano de publicação: 1996 Tipo de documento: Artigo