4-1BB signaling synergizes with programmed death ligand 1 blockade to augment CD8 T cell responses during chronic viral infection

V Vezys, P Penaloza-MacMaster, DL Barber… - The Journal of …, 2011 - journals.aai.org
V Vezys, P Penaloza-MacMaster, DL Barber, SJ Ha, B Konieczny, GJ Freeman, RS Mittler…
The Journal of Immunology, 2011journals.aai.org
Previous studies have identified the inhibitory role that the programmed death 1 (PD-1)
pathway plays during chronic infection. Blockade of this pathway results in rescue of viral-
specific CD8 T cells, as well as reduction of viral loads in mice chronically infected with
lymphocytic choriomeningitis virus (LCMV). We tested the effect of combining PD ligand 1
(PD-L1) blockade with an agonistic regimen that induces 4-1BB costimulation during chronic
LCMV infection. There is a boosting effect in the rescue of LCMV-specific CD8 T cell …
Abstract
Previous studies have identified the inhibitory role that the programmed death 1 (PD-1) pathway plays during chronic infection. Blockade of this pathway results in rescue of viral-specific CD8 T cells, as well as reduction of viral loads in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). We tested the effect of combining PD ligand 1 (PD-L1) blockade with an agonistic regimen that induces 4-1BB costimulation during chronic LCMV infection. There is a boosting effect in the rescue of LCMV-specific CD8 T cell responses after dual treatment with PD-L1 blockade and 4-1BB agonistic Abs when the amount and timing of 4-1BB costimulation are carefully controlled. When PD-L1–blocking Abs are given together with a single low dose of anti–4-1BB agonistic Abs, there is an enhanced and stable expansion of viral-specific CD8 T cells. Conversely, when blocking Abs to PD-L1 are given with a repetitive high dose of anti–4-1BB, there is an initial synergistic expansion of viral-specific CD8 T cells by day 7, followed by dramatic apoptosis by day 14. Viral control paralleled CD8 T cell kinetics after dual treatment. By day 7 posttreatment, viral titers were lower in both of the combined regimens (compared with PD-L1 blockade alone). However, whereas the high dose of anti–4-1BB plus PD-L1 blockade resulted in rebound of viral titers to original levels, the low dose of anti–4-1BB plus PD-L1 blockade resulted in a stable reduction of viral loads. These findings demonstrate the importance of carefully manipulating the balance between activating and inhibitory signals to enhance T cell responses during chronic infection.
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