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Trypanosoma cruzi, the protozoan parasite responsible for Chagas' disease, expresses on its surface an uncommon membrane-bound sialidase, known as trans-sialidase. trans-Sialidase is the product of a multigene family encoding both active and inactive proteins. We report here that an inactive mutant of trans-sialidase physically interacts with CD4(+) T(More)
CD8+ T lymphocytes play a critical role in immunity to Trypanosoma cruzi. However, the target molecules of this T cell subset have not been elucidated. In this work, we report the identification of an H-2Kb-restricted CTL epitope within two trypomastigote surface Ags encoded by members of the T. cruzi sialidase/trans-sialidase gene superfamily. Octapeptide(More)
Apoptosis mediated by Fas ligand (FasL) initiates inflammation characterized by neutrophilic infiltration. Neutrophils undergo apoptosis and are ingested by macrophages. Clearance of dead neutrophils leads to prostaglandin- and transforming growth factor-beta-dependent replication of Leishmania major in macrophages from susceptible mice. How L. major(More)
We investigated the role of neutrophil elastase (NE) in interactions between murine inflammatory neutrophils and macrophages infected with the parasite Leishmania major. A blocker peptide specific for NE prevented the neutrophils from inducing microbicidal activity in macrophages. Inflammatory neutrophils from mutant pallid mice were defective in the(More)
Class I MHC-restricted T cell responses have been shown to be critical for the development of immune resistance to Trypanosoma cruzi in mice. However, to date, no antigenic targets of this anti-parasite response have been characterized. We have analyzed the characteristics of potential T. cruzi CTL target molecules by expression of the model CTL target(More)
Activation-induced cell death (AICD) of CD4+ T lymphocytes was described in infection with Trypanosoma cruzi, but a role for AICD in modulating parasite spread in host cells has not been investigated. In this study, replication of T. cruzi in vitro in murine macrophage (Mphi) monolayers was investigated. Long term (5 to 13 day) replication of infective(More)
Trans-sialidase is a membrane-bound and shed sialidase from Trypanosoma cruzi, the protozoan parasite responsible for Chagas disease. We investigated the role of soluble trans-sialidase on host CD4+ T cell activation. Trans-sialidase activated naive CD4+ T cells in vivo. Both enzymatically active and inactive recombinant trans-sialidases costimulated CD4+ T(More)
We investigated the role of autophagy in infection of macrophages by Leishmania amazonensis. Induction of autophagy by IFN-gamma or starvation increased intracellular parasite load and the percentages of infected macrophages from BALB/c but not from C57BL/6 mice. In contrast, starvation did not affect the replication of either Leishmania major or(More)
A serological survey for canine visceral (VL) and American cutaneous leishmaniasis (ACL) has been carried out during 1984-1989, to assess the effects of the prophylactic measures adopted in areas where there was a risk of transmission of the diseases in Rio de Janeiro. A previous serological survey (1982/83) had detected serum positive dogs as well as the(More)
The effects of capsular polysaccharides, galactoxylomannan (GalXM) and glucuronoxylomannan (GXM), from acapsular (GXM negative) and encapsulate strains of Cryptococcus neoformans were investigated in RAW 264.7 and peritoneal macrophages. Here, we demonstrate that GalXM and GXM induced different cytokines profiles in RAW 264.7 macrophages. GalXM induced(More)