Hypoxia-inducible factors enhance CD8+ T cell effector responses to persistent antigen.. Mus musculus

Cytolytic activity by CD8+ cytotoxic T lymphocytes (CTL) is a powerful tactic in the elimination of intracellular pathogens and tumor cells. The destructive capacity of CTL is progressively dampened during chronic infection - yet the environmental cues and molecular pathways controlling immune “exhaustion” remain unclear. We find CTL immunity is regulated by the central transcriptional response to hypoxia, mediated by the von-Hippel-Lindau/Hypoxia-Inducible-Factor (VHL/HIF) pathway. Deletion of VHL, the primary negative regulator of HIF, leads to lethal CTL-mediated immunopathology during chronic infection, and VHL-deficient CTL display enhanced control of persistent viral infection and neoplastic growth. We find HIF and oxygen influence expression of pivotal CTL transcription, effector and costimulatory-inhibitory molecules, which is relevant to strategies to promote viral and tumor clearance. Overall design: To understand the role of the VHL/HIF pathway in regulating T cell responses to acute and persistant antigen in vivo, a mixture of ~10^4 WT and Vhl KO virus-specific CD8+ T cells (P14s) was transferred iv into uninfected WT host mice. After infection with either LCMV-Armstrong (acute viral infection) or LCMV-clone13 (persistent viral infection) we double-FACS isolated the responding P14 donor cells from pooled spleens from two sets of host mice to obtain duplicates for microarray for the four conditions, resulting in eight samples (2 WT Arm, 2 VHL KO Arm; 2 WT cl13, 2 VHL KO cl13) at 6 to 7 days post-infection. All conditions were sorted on KRLG1lo P14 cells. Note this was a mixed P14 transfer, so WT and KO cells were responding to infection in the same WT host mice to aid in normalizing effects such as antigen load and cytokine environment.