LEP and obesity disorder: Wang et al. (2019) reported an increase of leptin-induced PD-1 expression in obesity on CD8 T cells in humans, primates, and mice. Using the B16-F0 model, which is more immunogenic than B10-F10, they also found increased PD-1 expression on CD8 T cells in the tumor (Wang et al., 2019). In contrast, we did not observe increased expression of PD-1 on CD8 T cells in mice or humans. This is most likely because PD-1 expression in the tumor in SFD-fed mice already reached 90% in our experiments, which is in line with previous reports (Dyck et al., 2016; Juneja et al., 2017).