CD8A and neoplasm: Both Treg and Breg cells play a crucial role in shaping the tumor immunosuppressive environment, and both types of cells can inhibit the function of effector cells such as CD8+ T cells, Th1 cells, and NK cells through expressing PD-L1 and the release of cytokines such as IL-10, adenosine, IL-35, and TGF-β [103–106].