CD4 and cancer: Our results demonstrated that, except for the upregulation of sPD-L1 (Figure 1A), PD-1 expression on peripheral CD4+T cells (Figure 1B), and the apoptotic rate of peripheral PD-1+cells (Figure 1D) and PD-1+CD4+T cells (Figure 1E) were significantly increased in patients with cancer compared with healthy donors.