Cutting edge: identification of autoreactive CD4+ and CD8+ T cell subsets resistant to PD-1 pathway blockade

KE Pauken, CE Nelson, T Martinov… - The Journal of …, 2015 - journals.aai.org
KE Pauken, CE Nelson, T Martinov, JA Spanier, JR Heffernan, NL Sahli, CF Quarnstrom
The Journal of Immunology, 2015journals.aai.org
Programmed death-1 (PD-1) promotes T cell tolerance. Despite therapeutically targeting this
pathway for chronic infections and tumors, little is known about how different T cell subsets
are affected during blockade. We examined PD-1/PD ligand 1 (PD-L1) regulation of self-
antigen–specific CD4 and CD8 T cells in autoimmune-susceptible models. PD-L1 blockade
increased insulin-specific effector CD4 T cells in type 1 diabetes. However, anergic islet-
specific CD4 T cells were resistant to PD-L1 blockade. Additionally, PD-L1 was critical for …
Programmed death-1 (PD-1) promotes T cell tolerance. Despite therapeutically targeting this pathway for chronic infections and tumors, little is known about how different T cell subsets are affected during blockade. We examined PD-1/PD ligand 1 (PD-L1) regulation of self-antigen–specific CD4 and CD8 T cells in autoimmune-susceptible models. PD-L1 blockade increased insulin-specific effector CD4 T cells in type 1 diabetes. However, anergic islet-specific CD4 T cells were resistant to PD-L1 blockade. Additionally, PD-L1 was critical for induction, but not maintenance, of CD8 T cell intestinal tolerance. PD-L1 blockade enhanced functionality of effector T cells, whereas established tolerant or anergic T cells were not dependent on PD-1/PD-L1 signaling to remain unresponsive. This highlights the existence of Ag-experienced T cell subsets that do not rely on PD-1/PD-L1 regulation. These findings illustrate how positive treatment outcomes and autoimmunity development during PD-1/PD-L1 inhibition are linked to the differentiation state of a T cell.
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