Phenotypic Features of Peripheral Blood Leucocytes During Early Stages of Human Infection with Trypanosoma cruzi

Abstract

We performed a cross-sectional flow cytometric analysis of peripheral blood mononuclear cells to evaluate human immunologic status during early stages of Trypanosoma cruzi infection in children. We identified major immunological features corresponding to three proposed phases of disease: early acute (EA) phase, late acute (LA) phase and recent chronic (RC) phase. EA phase was accompanied by expansion of conventional B cells, up-regulation of CD54 on monocytes and down-regulation of CD54 on T cells and not associated with monocyte-activation phenotypes or changes of natural killer (NK) population. LA phase was characterized by a selective increase in a distinct lineage of NK cells (CD16 þ CD56 -), as well as a persistent expansion of B cells and downregulation of CD54 on T cells. RC phase showed persistent low levels of CD54 molecule on T cells and an increase of B cells, mainly triggered by expansion of the B1-cell subset, as well as increased expression of human leucocyte antigen (HLA-DR) by monocytes. These findings reinforce the hypothesis that T. cruziderived antigens are able to activate NK cells before the development of T-cellmediated immunity. Moreover, our data support previous findings of increased levels of B1 lymphocytes during human Chagas' disease and show that this event is already present during initial stages of chronic infection.

Etiological treatment during early chronic indeterminate Chagas disease incites an activated status on innate and adaptive immunity associated with a type 1-modulated cytokine pattern

“…Despite several reports of higher T-cell activation during chronic Chagas disease [14e16], we have previously demonstrated that E-IND is characterized by a T-cell-independent immunity with no changes in the frequency of circulating HLA-DR þ T-cells [17]. Because HLA-DR is commonly referred to as a late-stage activation cell surface marker, we have further focused the T-cell activation issue by characterizing the expression of an early activation marker, CD69, aiming to evaluate the T-cell activation profile before and after the Bz-treatment.…”

The Unsolved Jigsaw Puzzle of the Immune Response in Chagas Disease

“…An increase in the frequency of circulating B cell seems to occur during the late acute phase of T. cruzi infection in humans, but only becoming significant at the beginning of the chronic phase (100). Nonetheless, it has been proposed that, in patients with established chronic Chagas disease, the number of CD19 + cells is not different from that of non-infected individuals (101, 102), suggesting a subsequent contraction of this population.…”

Innate immunity and regulatory T-cells in human Chagas disease: what must be understood?

“…With the aim of contributing to this field of investigation, studies have been developed to characterise immunological biomarkers in patients presenting distinct clinical manifestations of the disease (Reis et al 1993, Dutra et al 1994, 1996, Lemos et al 1998, Gomes et al 2003, Sathler-Avelar et al 2003, Souza et al 2004, Vitelli-Avelar et al 2005, 2006, 2008. Additionally, other investigators have also focused on what impact etiological treatment with benznidazole (Bz) may have on the anti-T. cruzi immune response (Bahia-Oliveira et al 2000, Sathler-Avelar et al 2006, 2008, Vitelli-Avelar et al 2008.…”