CD48 and neoplasm: In addition, consistent with Nishino et al. [4, 33], we also observed a strong positive correlation between infiltrating immune cells and immune checkpoints, such as CD48, HAVCR2 and PDCD1LG2, which is an important intrinsic immune surveillance escape mechanism; the PD-1, CTLA-4, BTLA, HAVCR2, and Lag3 have been proved to be the potent immune checkpoints to mediate tumor immunosuppression [34, 35].