PDCD1 and Sepsis: Importantly, animal models have demonstrated enhanced antibody production and improved survival in PD-1 knockout mice in CLP mice, and several phase 1B/2 clinical trial studies have confirmed that nivolumab, a PD-1 monoclonal antibody, has good safety and tolerability in sepsis patients (Huang et al., 2009; Hotchkiss et al., 2019a; Hotchkiss et al., 2019b; Watanabe et al., 2020).