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  • 1
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Several studies have demonstrated that different clinical manifestations of human Chagas' disease are associated with distinct and complex host–parasite relationships directly involving the immune system. In this context, it has been proposed that tissue damage might be more severe in the absence of regulatory mechanisms that involve both innate and adaptive immune responses. Herein, we describe a descriptive phenotypic profile focusing on the frequency of major regulatory T cells [CD4+CD25high and natural killer T (NKT) lymphocytes] in different clinical forms of Chagas' disease. Ex vivo immunophenotyping of whole blood demonstrated that the indeterminate clinical form displays a higher frequency of both CD4+CD25high and NKT regulatory cells (CD3+CD16–CD56+), associated with increased levels of circulating cytotoxic NK cells (CD3–CD16+CD56+ and CD3–CD16+CD56dim NK cells). By contrast, the increased percentage of activated CD8+HLA-DR+ T-cell subset was exclusively associated with severe clinical forms of Chagas' disease. We hypothesize that regulatory T cells may be able to control the deleterious cytotoxic activity in the indeterminate clinical form by inhibiting the activation of CD8+HLA-DR+ T cells. The lack of regulated populations in cardiac and digestive clinical forms could account for impaired immune response that culminates in strong cytotoxic activity and tissue damage.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of this study was to examine three distinct groups of schistosomiasis patients and to determine whether cell phenotype profiles could be correlated with the different clinical forms of the disease. The data obtained indicate that Schistosoma mansoni infected patients have a lower percentage of CD3+ T cells than do non-infected individuals. Interestingly, infected patients presented more than twice the mean percentage of circulating activated T cells (CD3+HLA-DR+) when compared to the control group. Examination of T lymphocyte subpopulations showed that patients with the severe hepatosplenic form (HS) of the disease had lower levels of both CD8High+ and CD8Low+ cells when compared to the other groups of patients. All infected individuals had a higher percentage of circulating B cells, with an increase in the CD5+ B cell population that was more evident in the HS group. The data presented here are evidence to support a relationship between the hepatosplenic form of the disease, a decrease on the CD8+ cell population and an elevation on CD5+B cells.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We investigated the cytokine profile of cells of the innate immune response and its association with active (ACT), asymptomatic (AS) and cured (CUR) human visceral leishmaniasis (VL), as well as noninfected (NI) subjects. The frequency of cytokine-producing cells was determined after short-term in vitro incubation of whole peripheral blood samples with soluble Leishmania antigen (SLA). Our data demonstrated a predominant type 2 cytokine profile in NI and ACT. In NI, we observed an increase of IL-4+ neutrophils, IL-10+ eosinophils besides a decrease of tumour necrosis factor (TNF)-α+ eosinophils/monocytes. Yet in ACT, we observed an increase of IL-4+ neutrophils and natural killer (NK) cells and IL-10+ monocytes, a reduced frequency of IL-12+ and IFN-γ+ eosinophils and lower levels of TNF-α+ and IL-12+ monocytes. AS presented a mixed profile, characterized by an increase of IFN-γ+ neutrophils/eosinophils and NK cells, of IL-12+ eosinophils/monocytes, as well as increase of IL-4+ neutrophils and NK cells and IL-10+ eosinophils/monocytes. In contrast, CUR was characterized by a type 1 response with an increase of IFN-γ+ neutrophils/eosinophils and NK cells, associated with an increase in IL-12+ monocytes. In conclusion, we show a correlation between innate immune cytokine patterns and clinical status of VL, suggesting that these cells, in addition to other factors, may contribute to the cytokine microenvironment in which Leishmania-specific T cells are primed and to disease outcome.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: There are differences between children and adults in certain aspects of the Helicobacter pylori (HP) infection, among them the lower titre of IgG antibodies anti-HP in the former group. Thus, we investigated by means of flow cytometry CD4+/CD3+ (CD4+T), CD8+/CD3+ (CD8+T) and CD19+/CD3– (B) cells, activation/co-stimulatory markers (CD4+/HLA-DR+, CD4+/CD28+, CD8+/HLA-DR+ and CD8+/CD28+) and by means of ELISA IgG anti-HP antibodies in the peripheral blood from HP-positive and -negative children and adults. An increased CD4+/CD28+ and CD8+/CD28+ percentage and number of CD4+/CD3+ cells were seen in infected adults. Conversely, no difference was observed between infected and noninfected children, but when they were stratified by age, an increased CD4+/CD28+ cell percentage was seen in the HP-positive group older than 10 years. The mean level of IgG anti-HP was lower in younger infected children, increased with age and correlated with CD4+ cells. Our data suggest that the immune response to HP infection vary according to the age. Low percentage of activated CD4+ cell may contribute to the lower level of serum IgG anti-HP observed in younger infected children. In addition, the CD4+ cell participation during the infection seems to begin after 10 years old, when the immune response becomes similar to that seen in adults.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 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+CD56–), as well as a persistent expansion of B cells and down-regulation 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. cruzi-derived antigens are able to activate NK cells before the development of T-cell-mediated 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.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A histopathological and immunophenotypic study was performed on the spleen of patients with hepatosplenic (HS) schistosomiasis mansoni. Morphological data demonstrated that all HS patients presented features related to Schistosoma mansoni-induced splenomegaly, such as red pulp congestion and atrophy/hyperplasia of white pulp. The morphological diversity of the white pulp seems to be associated with the expansion of activated CD4+ T-cell subpopulation. The data obtained suggest that the spleen is an important site for T-cell activation during severe chronic infection with S. mansoni. In addition, we have compared the cell populations/subpopulations presented in the peripheral blood with that observed in the spleen of patients with HS schistosomiasis mansoni. We observed a significant increase in the percentage of activated CD4+HLA–DR+ and CD8+HLA–DR+ T cells in both the spleen and the peripheral blood of HS patients in comparison with noninfected individuals (NOR). These data suggest an exchange of cells between these two compartments. However, we observed normal expression of the CD28 molecule by CD8+ T cells in the spleen, despite a lower percentage of these cells in the peripheral blood. This finding supports the hypothesis that the decrease in CD28 expression, by CD8+ cells, is an event that takes place outside the spleen during human schistosomiasis infection. The most important conclusion is the fact that the analysis of T-cell activation in the peripheral blood reflects the major immunological reactivity that occurs in the spleen during human schistosomiasis and that the morphological aspects of the spleen may reflect the functional activity of T cells. The specificities of T cells and the roles they may play in the pathogenesis during chronic schistosomiasis now need to be determined.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 43 (1996), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A balanced host-parasite interaction during Trypanosoma cruzi infection allows for the establishment of a chronic infection that can last for many years. T cells are a major element responsible for parasite specific and non-specific immunityduring the complex immune response of the host. However, the sub-populations of T cells involved in the response, as well as the exact mechanisms through which those cells are activated or rendered unresponsive, are not well defined. It is known thatco-stimulatory signals, some of which are mediated via CD28, are of critical importance in the triggering of appropriate T cell responses. In this study the authors performed double-labelling studies to determine the frequency of expression of CD28 byCD4+ and CD8+ T lymphocytes in the peripheral blood of patients with Chagas’ disease. The results show that chagasic patients throughout the spectrum of chronic clinical forms of the infection have significantly higher meanfrequencies of CD4+CD28– and CD8+CD28– T cells, as compared with non-chagasic individuals. Considering the importance of CD28 for T-cell activation, the observed down-regulation or loss of CD28during infection may indicate a possible basis for observed immunoregulatory events or distinct stages of T-cell activation in this infection. Recent evidence from patients with HIV/AIDS indicates that CD28– cell populations are morelikely to undergo apoptosis, and increased apoptosis has been observed in experimental Chagas disease.
    Type of Medium: Electronic Resource
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