Blocking intrahepatic deletion of activated CD8+ T cells by an altered peptide ligand

We show that the intrahepatic deletion of CD8+ T cells by SIINFEKL peptide results in loss of in vivo cytotoxic T lymphocyte function. In contrast we show that a low affinity peptide (G4) does not result in intrahepatic deletion of CD8+ T cells. High concentrations G4 peptide can however block intrahepatic deletion of activated CD8+ T cells, and prevent loss of in vivo cytotoxicity due to SIINFEKL peptide. This is the first demonstration of blocking of SIINFEKL peptide induced CD8+ T cell deletion in the liver, with enhancement of in vivo cytotoxicity.