Differential Phenotypic and Functional Profiles of TcCA-2 -Specific Cytotoxic CD8+ T Cells in the Asymptomatic versus Cardiac Phase in Chagasic Patients

It has been reported that the immune response mediated by T CD8+ lymphocytes plays a critical role in the control of Trypanosoma cruzi infection and that the clinical symptoms of Chagas disease appear to be related to the competence of the CD8+ T immune response against the parasite. Herewith, in silico prediction and binding assays on TAP-deficient T2 cells were used to identify potential HLA-A*02:01 ligands in the T. cruzi TcCA-2 protein. The TcCA-2-specific CD8+ T cells were functionality evaluated by Granzyme B and cytokine production in peripheral blood mononuclear cells (PBMC) from Chagas disease patients stimulated with the identified HLA-A*02:01 peptides. The specific cells were phenotypically characterized by flow cytometry using several surface markers and HLA-A*02:01 APC-labeled dextramer loaded with the peptides. In the T. cruzi TcCA-2 protein four T CD8+ epitopes were identified which are processed and presented during Chagas disease. Interestingly, a differential cellular phenotypic profile could be correlated with the severity of the disease. The TcCA-2-specific T CD8+ cells from patients with cardiac symptoms are mainly effector memory cells (TEM and TEMRA) while, those present in the asymptomatic phase are predominantly naive cells (TNAIVE). Moreover, in patients with cardiac symptoms the percentage of cells with senescence features is significantly higher than in patients at the asymptomatic phase of the disease. We consider that the identification of these new class I-restricted epitopes are helpful for designing biomarkers of sickness pathology as well as the development of immunotherapies against T. cruzi infection.This work was supported by grants SAF2012-35777 and SAF2013-48527-R from Programa Estatal I+D+i (MINECO); Network of Tropical Diseases Research RICET, grants RD12/0018/0021 and RD12/0018/0018 (MSSSI, Spain) and FEDER. MS and BC were also supported by grant FIS, 2009SGR385 from ISCIII (MSSSI, Spain). Coauthor Concepción Marañón is employed by Genomic Medicine Department, GENYO. Centre for Genomics and Oncological Research: Pfizer / University of Granada / Andalusian Regional Government. Centre for Genomics and Oncological Research: Pfizer / University of Granada / Andalusian Regional Government provided support in the form of salaries for author Concepción Marañón, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the author contributions section.Peer reviewe