CD8+ cells and natural cytotoxic activity among spleen, blood, and heart lymphocytes during the acute phase of Trypanosoma cruzi infection in rats

Abstract

The infection developed by Wistar Furth rats inoculated with the Y strain of Trypanosoma cruzi was the experimental model used in our study. The results showed that this infection altered considerably the CD4/CD8 lymphocyte subset ratio and the natural cytotoxic activity of mononuclear cells in the spleen, blood, and myocardial tissue. Concomitantly, an expansion of the number of cells expressing major histocompatibility complex (MHC) class II antigens was observed, as well as spontaneous development of high levels of blast cells, mainly in the spleen. The inflammatory infiltration of the myocardium, made up essentially of CD8+ cells (cytotoxic/suppressor T cells, natural killer cells), was initially found at 9 days postinfection, spread continuously, and was observed until the death of the animals at about 18 days postinfection. T. cruzi infection also enhanced the natural killer activity of mononuclear cells in the blood, spleen, and myocardium. Sorting these cells by affinity columns showed that the natural killer function was performed exclusively by the CD8+ population, which did not express MHC class II antigens. It was shown that the polyclonal T-lymphocyte activation induced by T. cruzi infection results in a wide distribution of CD8+ cells with enhanced natural cytotoxic activity in the spleen, blood, and cardiac tissue.

Circulating lymphocyte subpopulations and activated T and B cells in patients with chagasic and non-chagasic myocardiopathy

“…While HLA-ABC antigen expression is enhanced on the myocardial cells of chronic chagasic patients, suggesting a possible role for these cells as targets for CD81 cytolytic lymphocytes, HLA-DR antigens are not observed in the myocardium of these patients (21). These data might explain the significant decrease in circulating CD31/CD711 and CD81/CD251 activated T lymphocytes but not in CD41 cells found in our chronically infected chagasic patients and further support the observation of a selective inflammatory migration of T lymphocytes into damaged cardiac tissue (23).…”

“…Inflammatory cell infiltration is the characteristic lesion developed in the myocardium during the acute and chronic phases of T. cruzi infection. Heart lesions in patients with chronic Chagas' disease are composed predominantly by CD81 T lymphocytes (20) and large amounts of CD31 and CD81 T cells are sequestered in the cardiac tissue of T. cruzi-infected mice (23). CD4 and CD8 molecules participate in lymphocyte adhesion to antigen-presenting cells involving MHC class II and class I products, respectively (3,24).…”

Cytotoxicity in patients with different clinical forms of Chagas’ disease

“…Our data demonstrate that NK cells are the predominant cells in killing K562 target cells in Chagas' disease patients. NK activity has also been detected in the spleens, blood and hearts of acutely T. cruzi-infected rats [16].The exact role that these non-specific cytolytic mechanisms play in protective immunity to this parasite remains to be determined. The fact that such activity can be induced by specific in vitro antigen challenge suggests that such a mechanism might also operate in vivo and could contribute to the development of chagasic tissue lesions.…”

Cytokine Production in Hearts of Trypanosoma cruzi‐Infected CBA Mice: Do Cytokine Patterns in Chronic Stage Reflect the Establishment of Myocardial Pathology?

“…Previous studies of human infection and experimental models of T. cruzi infection have indicated a predominance of CD8 cells in the heart during acute and chronic infection [19][20][21][22][23][24], although some studies have reported a dominance of CD4 cells during the course of infection [25,26].…”