Evaluation of IFN‐γ production by CD8⁺ T lymphocytes in response to the K1 peptide from KMP‐11 protein in patients infected with Trypanosoma cruzi

Abstract

The cellular response mediated by MHC class I restricted CD8+ T cells has been shown to be crucial in the control of Chagas disease. The K1 peptide derived from T. cruzi KMP-11 protein has a high binding affinity to the HLA-A*0201 molecule. Nevertheless, it is not known whether this peptide is processed and displayed as an MHC class I epitope during natural infection by T. cruzi. The aim of this study was to evaluate, by ELISPOT assay, the ability of K1 peptide to activate CD8+ T lymphocytes to produce IFN-gamma. Therefore, CD8+ T lymphocytes from 22 HLA-A*0201+ individuals, 12 chronic chagasic patients and 10 uninfected controls, were analysed. The results revealed that two of the chagasic patients had IFN-gamma-secreting CD8+ T cells that were able to respond to K1 peptide with a relative frequency of 110 and 230 per million CD8+ T cells. In contrast, none of HLA-A*0201+ uninfected controls responded to K1 peptide. Responses to HLA-A*0201 restricted peptide from the influenza matrix protein were found in six chagasic patients and four uninfected controls with an average frequency of 175 and 111 cells per million CD8+ T cells, respectively. Moreover, a flow cytometric assay for degranulation showed that chagasic responders had K1-specific cytotoxic CD8+ T cells. It is shown here for the first time that the K1 peptide is efficiently processed, presented and recognized by CD8+ T lymphocytes during the natural course of Chagas disease.

Deprotection Reagents in Fmoc Solid Phase Peptide Synthesis: Moving Away from Piperidine?

“…Circular dichroism showed an alpha helix tendency for all four peptides (Figure 2), in accordance with previous reports for NBC155 and NBC1951 [16,19]. Pepfold3 server [20] prediction for the secondary structure also showed the alpha helix as the best model for all four peptides.…”

Viejos y nuevos conceptos en inmunidad a parásitos

“…Se han descrito epítopos de unión a HLA de clase I en proteínas parasitarias como en las transialidasas (Martin et al, 2006) y la proteína de 11 kDa de membrana de cinetoplástidos o KMP-11 (Diez et al, 2006), especialmente secuencias de unión al alelo HLA-A2. Con la estimulación usando péptidos sintéticos que representan dichos epítopos se evalúa la producción de citocinas como IFNγ,y mediante el uso tetrámeros de HLA/ péptidos unidos a marcadores fluorescentes, se puede rastrear las células específicas de sangre o tejidos.…”

T cells responding to Trypanosoma cruzi detected by membrane TNF‐α and CD154 in chagasic patients

“…However, in chronic parasitic infections, IFN‐γ expression significantly fluctuates 7, 8, 9, 10. Indeed, the impairment of IFN‐γ secretion is part of the “T cell exhaustion” phenomena in which cellular functions such as cytotoxic capacity, cytokine production, and proliferative potential are sequentially diminished as a result of continuous antigen exposure 11, 12.…”