Expression regulation and function of PD-1 and PD-L1 in T lymphoma cells

•Human T lymphoma cells express both PD-1 and PD-L1.•TCR signaling activates PD-1 but represses PD-L1 expression in T lymphoma.•PD-L1 promotes T lymphoma growth in vivo.•PD-1 signaling pathways is impaired in vitro but promotes tumor growth in vivo. T lymphoma cells may constitutively express PD-1 and PD-L1. The relative role of PD-1 and PD-L1 in T lymphoma is incompletely understood. We report here that PD-1+ PDL-1+ human T lymphoma cells exhibit constitutive hyperactivation of the TCR signaling and do not respond to PD-L1-mediated suppression in vitro. Knocking out PD-1 or PD-L1 has no effects on T lymphoma cell apoptosis and proliferation in vitro, but significantly increased tumor-bearing mouse survival. Our findings determine that the constitutively active TCR signaling pathway maintain T lymphoma cell growth in vitro and that both PD-1 and PD-L1 promote T lymphoma growth in vivo.