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The innate immune system is the first mechanism of vertebrate defense against pathogen infection. In this study, we present evidence for a novel immune evasion mechanism of Trypanosoma cruzi, mediated by host cell plasma membrane-derived vesicles. We found that T. cruzi metacyclic trypomastigotes induced microvesicle release from blood cells early in infection. Upon their release, microvesicles formed a complex on the T. cruzi surface with the complement C3 convertase, leading to its stabilization and inhibition, and ultimately resulting in increased parasite survival. Furthermore, we found that TGF-β-bearing microvesicles released from monocytes and lymphocytes promoted rapid cell invasion by T. cruzi, which also contributed to parasites escaping the complement attack. In addition, in vivo infection with T. cruzi showed a rapid increase of microvesicle levels in mouse plasma, and infection with exogenous microvesicles resulted in increased T. cruzi parasitemia. Altogether, these data support a role for microvesicles contributing to T. cruzi evasion of innate immunity.
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil.
This article was published in the following journal.
Name: Journal of immunology (Baltimore, Md. : 1950)
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Methods used by pathogenic organisms to evade a host's immune system.
A hemoflagellate parasite affecting domestic and wild animals, as well as humans and invertebrates. Though it induces an immune response, it is non-pathogenic in humans and other vertebrates. It is cross-reactive with TRYPANOSOMA CRUZI and can thus cause false positives for CHAGAS DISEASE.
A B7 antigen subtype that inhibits the costimulation of T-cell activation, proliferation, cytokine production and development of cytotoxicity. The over expression of this protein in a variety of tumor cell types suggests its role in TUMOR IMMUNE EVASION.
A genus of the subfamily TRIATOMINAE. Several species are vectors of TRYPANOSOMA CRUZI.
An inhibitory B7 antigen that has specificity for the T-CELL receptor PROGRAMMED CELL DEATH 1 PROTEIN. CD274 antigen provides negative signals that control and inhibit T-cell responses and is found at higher than normal levels on tumor cells, suggesting its potential role in TUMOR IMMUNE EVASION.
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (such as bacteria, fungi, parasites, and viruses) and chemicals. Antibodies may be produc...
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