SPDL1 and lymphoma: The results of many studies consistently show that sPD-L1 levels are higher in PTCL than in healthy volunteers and that plasma or serum sPD-L1 levels are positively correlated with PD-L1 expression in lymphoma tissue, suggesting that sPD-L1 levels are potential plasma biomarkers for predicting prognosis in patients with PTCL (Wang et al., 2016; Nagato et al., 2017; Shen et al., 2019; Zhang X. et al., 2019; Li et al., 2020).