[HTML][HTML] B7-H1 Blockade Increases Survival of Dysfunctional CD8+ T Cells and Confers Protection against Leishmania donovani Infections

T Joshi, S Rodriguez, V Perovic, IA Cockburn… - PLoS …, 2009 - journals.plos.org
T Joshi, S Rodriguez, V Perovic, IA Cockburn, S Stäger
PLoS pathogens, 2009journals.plos.org
Experimental visceral leishmaniasis (VL) represents an exquisite model to study CD8+ T cell
responses in a context of chronic inflammation and antigen persistence, since it is
characterized by chronic infection in the spleen and CD8+ T cells are required for the
development of protective immunity. However, antigen-specific CD8+ T cell responses in VL
have so far not been studied, due to the absence of any defined Leishmania-specific CD8+
T cell epitopes. In this study, transgenic Leishmania donovani parasites expressing …
Experimental visceral leishmaniasis (VL) represents an exquisite model to study CD8+ T cell responses in a context of chronic inflammation and antigen persistence, since it is characterized by chronic infection in the spleen and CD8+ T cells are required for the development of protective immunity. However, antigen-specific CD8+ T cell responses in VL have so far not been studied, due to the absence of any defined Leishmania-specific CD8+ T cell epitopes. In this study, transgenic Leishmania donovani parasites expressing ovalbumin were used to characterize the development, function, and fate of Leishmania-specific CD8+ T cell responses. Here we show that L. donovani parasites evade CD8+ T cell responses by limiting their expansion and inducing functional exhaustion and cell death. Dysfunctional CD8+ T cells could be partially rescued by in vivo B7-H1 blockade, which increased CD8+ T cell survival but failed to restore cytokine production. Nevertheless, B7-H1 blockade significantly reduced the splenic parasite burden. These findings could be exploited for the design of new strategies for immunotherapeutic interventions against VL.
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