CD8⁺ T-cells recognizing the VNHRFTLV ASP2 <i>T. cruzi</i> peptide are enriched in the cardiac tissue.

<p>C57BL/6 mice were infected with 100 bt of the Colombian strain of <i>T. cruzi</i> and the anti-parasite immune response in the spleen and cardiac tissue was assessed. (<b>A</b>) Representative spots formed after stimulation of spleen cells from noninfected (NI) and <i>T. cruzi</i>-infected mice at 45 and 120 dpi with H-2K^b-resctricted VNHRFTLV peptide. The number of CD8⁺IFNγ⁺ as determined by <i>ex vivo</i> ELISpot were analyzed and compared with parasitemia and CK-MB activity levels in the serum. (<b>B</b>) Representative histogram profiles of <i>in vivo</i> cytotoxicity assay showing the specific lysis of H-2K^b-resctricted VNHRFTLV peptide-labeled CFSE^high cells from NI controls and <i>T. cruzi</i>-infected C57BL/6 mice at 45 and 120 dpi. The frequencies of <i>in vivo</i> specific lysis of with H-2K^b -resctricted VNHRFTLV peptide-labeled target cells in <i>T. cruzi</i>-infected C57BL/6 mice at 15, 30, 45, 60, 90 and 120 dpi were analyzed and compared with parasitemia and CK-MB activity levels in the serum. The peak of parasitemia and the maximum CK-MB activity are highlighted (dotted line). Each circle and vertical lines represent the mean ± standard deviation (SD) of the studied group (5–7 animals/time point). These data represent three independent experiments. (<b>C</b>) Frequency of double-positive CD8⁺ H-2K^b /VNHRFTLV⁺ cells [R1 (SSCxFSC) gated] of spleen and heart of NI and <i>T. cruzi</i>-infected C57BL/6 mice at 40 dpi. (<b>D</b>) Frequencies of double-positive CD8⁺ H-2K^b /VNHRFTLV⁺ cells [R1 (SSCxFSC) gated] of spleen, peripheral blood and heart of NI and <i>T. cruzi</i>-infected C57BL/6 mice at 30, 45 and 120 dpi. Representative flow ctometry profiles and mean ± SD of two or three animals per group. Bars represent the mean of two or three pools of 5 mice per pool.