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. 2022 Apr 19;13:835510. doi: 10.3389/fphar.2022.835510

FIGURE 2.

FIGURE 2

Attenuation and activation of T lymphocytes via CTLA4 and PD-1/PD-L1 axes. APCs can capture neoantigens and present to T lymphocytes on MHC molecules. The activated T cells, receiving the neoantigens, will migrate to the tumor bed from lymph nodes. The activation of T cells can be accelerated by costimulatory signals via the combination of B7 with CD28. The attenuation of T cells is managed by inhibitory axes, which are CTLA4/B7 and PD-1/PD-L1. The tumor cells can recognize the IFN-γ via the IFN-γ receptor, which promotes the expression of PD-L1 on their surfaces. PD-L1 can help tumor cells to escape the attack of T cells. The monoclonal antibodies of those immune checkpoints, like CTLA4 (ipilimumab®), PD-L1 (atezolizumab®, avelumab®, and durvalumab®), and PD-1 (nivolumab®, pembrolizumab®, and cemiplimab®), can stop the attenuation of T cells, making activated T cells to attack tumor cells. Modified and reprinted from Han J. R. et al. (2019). Copyright © The Author(s). 2019. Reproduction with permission from The Author(s). 2019 Open Access.