Proliferative dysfunction in chronically activated T lymphocytes from chagasic patients (70.1)

Abstract

Abstract Background: Trypanosoma cruzi persistence has been associated with cardiac and gastrointestinal tissue damage in nearly 30% of the infected individuals; however, the pathogenic mechanisms are yet unknown. This study’s goal was to compare the activation status and proliferative capacity of T lymphocytes among chronic chagasic patients and uninfected controls. Methodology: Twenty-seven chronic chagasic patients, 20 healthy individuals and 28 non-chagasic cardiomyopathy donors were analyzed. Peripheral blood cells were stained with CD3, CD4, CD8, CD28, HLA-DR and CD38. PBMCs were labeled with CFSE and co-cultivated with PHA or T. cruzi lysate; at the fifth day post-stimulation cells were stained for CD3, CD4 and CD8. Results: Chagasic patients displayed higher frequencies of CD4+ (P=0.0001) and CD8+ (P=0.0002) T cells co-expressing HLA-DR and CD38 in comparison with healthy and non-chagasic cardiomyopathy donors. Also, the former group exhibited lower percentages of CD8+/CD28+ T lymphocytes (P=0.0005). After 5 days of stimulation, the proliferation index was lower in both CD4+ (P=0.01) and CD8+ (P=0.04) PHA-stimulated T cells from chagasic donors when compared with both control groups. Conclusions: Despite their increased activation status, the T lymphocytes from chagasic donors displayed reduced proliferative capacity after mitogenic stimulation, corroborating a dysfunctional cellular immune response in the chronic stages of the disease.