Trypanosoma cruzi: Tc52 released protein-induced increased expression of nitric oxide synthase and nitric oxide production by macrophages.

Trypanosoma cruzi target molecules that might regulate the host immune responses have not yet been fully identified. In the present study, we demonstrate that the parasite-released molecule (Tc52) was able to synergize with IFN-gamma to stimulate nitric oxide production by macrophages. This synergistic effect was also observed at the level of inducible nitric oxide synthase gene expression. Furthermore, Tc52 was also shown to induce gene expression for IL-1alpha, IL-12, and IL-10. Moreover, the combination of Tc52 and IFN-gamma down-regulates IL-1alpha and IL-10 gene expression, but not IL-12. Isotype profiles and Tc52 or anti-CD3-induced T cell proliferation were also analyzed, indicating that active immunization with Tc52 partially relieves the immunosuppression observed during the acute phase of the disease. Moreover, under conditions of experimental infection, the Tc52 appears immunologically silent, failing to elicit Ab response and lymphocyte proliferation during the initial acute phase infection. Following active immunization, Tc52 was capable of stimulating T cell proliferation and Ab production with a predominance of IgG1, IgG2a, IgG2b, IgG3, and to a lesser extent IgA. Taken together, these results demonstrate that T. cruzi Tc52-released Ag could be involved in the immunoregulatory processes. The immune response against Tc52 that appears late in the T. cruzi infection may play a role in the modulation of its biological function(s).

Trypanosoma cruzi: a 52-kDa protein sharing sequence homology with glutathione S-transferase is localized in parasite organelles morphologically resembling reservosomes.

We have previously isolated and characterized a Trypanosoma cruzi cDNA encoding a polypeptide with a molecular mass of 52 kDa (Tc52) sharing significant homology to glutathione S-transferase. In the present study, by molecular and immunological approaches, we showed that Tc52 is preferentially expressed by dividing forms of the parasite: (e.g., epimatigotes and amastigotes). Moreover, we could identify the reactive antigen in different T. cruzi strains. A different pattern of reactivity on immunoblots was observed in the case of Trypanosoma rangeli. Furthermore, immunofluorescence assays using T. cruzi epimastigote culture forms revealed that the reactive antigen is localized within cytoplasmic organelles morphologically ressembling the structures previously designated as the reservosome found mostly at the posterior end of the parasite. Furthermore, the antibodies did not react against trypomastigotes which emerged from infected fibroblasts, whereas amastigotes showed polar fluorescence. Immunogold labeling and electron micrographs further revealed that the Tc52 protein is mainly associated with organelles composed of a large network of multivesicular structures, the latter being more abundant in epimastigotes. Taken together, these results demonstrated that Tc52 is associated with organelles composed of a multivesicular network and appears to be developmentally regulated, being fully expressed by parasite dividing forms.

[Quantification of number and function of mononuclear cells. Fc gamma receptors in children with protein-calorie malnutrition (PCM)]. / Cuantificación del número y la función de las células mononucleares. RFc gamma de niños con desnutrición proteico-calórica (DPC).

Several kind of cells T membrane receptors have been recognized, between them immunoglobulins heavy chains receptors mu and gamma, they act in the antigen recognition, they are subpopulations-cells T surface-matched too. In the malnutrition protein-calorie (MPC) immunologic alterations were observed, in both cellular immune and humoral immune, for example: The immunoglobulins are increased and cellular response towards antigens is decreased. This failure can be due to dysfunction in the lymphocyte T-subpopulation. So we research if there are different number, percent and function of lymphocytes T subpopulations between children with MPC and health infant. We observed an increment of lymphocytes T gamma in number and percent in children with MPC compared with health infant (p < 0.05) However, the lymphocytes T and subpopulation gamma response to phytohemagglutinin was bad. These findings are concordant with the literature about increased in lymphocyte T gamma of children with MPC. Additionally we observed a dysfunction in this subpopulation.