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Fig. 3 | Cell & Bioscience

Fig. 3

From: Tumor cells versus host immune cells: whose PD-L1 contributes to PD-1/PD-L1 blockade mediated cancer immunotherapy?

Fig. 3

A comprehensive understanding of PD-L1 on both tumor cells and immune cells in working concretely to contribute to anti-PD-L1 blockade mediated therapeutic effects. PD-L1 expressed on either tumors or host immune cells contributes to the inhibition of T cell activation, which can be released through blocking PD-L1 signaling by antibodies. During antitumor immune responses, antigen-presenting cells (APCs, especially dentritic cells and macrophages) uptake tumor antigens and activate T cells inside tumors. PD-L1 blockade on both APCs and tumor cells within the tumor microenvironment enhances T cell activation. APCs with up-taken tumor antigens migrate from the tumor tissues to the peripheral lymphoid organs to activate T cells outside tumors. Peripherally activated tumor-specific effector T cells infiltrate into the tumor sites and immunologically eliminate tumors. Peripheral PD-L1 signaling in draining lymph nodes may significantly hamper the antitumor immune responses by limiting effector T cell trafficking. Thus, PD-L1 blockades both inside and outside tumors may jointly promote host immunity to achieve effective therapy. Therefore, PD-L1 expression on either tumors or immune cells could be predictive of sensitivity to therapeutic agents targeting the PD-1/PD-L1 axis. Teff, effector T cell

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