In addition, Pearson’s correlation analysis demonstrated that sPD-L1 expression levels were significantly and positively correlated with the apoptosis of PD-1+ cells (r2 = 0.1774, p=0.0321, Figure 1G) and PD-1+CD4+ T cells (r2 = 0.1994, p=0.0222, Figure 1H) in the 26 patients with cancer, but not with that of PD-1+CD8+ T cells (r2 = 0.09412, p=0.2310, Figure 1I) in 17 patients with cancer. Here, CD4 is linked to cancer.