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. 2023 May 19;13(6):2346–2368. doi: 10.1016/j.apsb.2023.05.016

Figure 3.

Figure 3

Mechanisms of CTLA-4 and PD1/PD-L1 blockades. (A) CTLA-4 competes with CD28 to bind to B7, inhibiting T-cell function. Anti-CTLA-4 antibodies block CTLA-4 and B7 ligation and prevent inhibition of T cell function. (B) Programmed cell death 1 (PD1) on activated T cells binds to its ligand (PD-L1) on the antigen-presenting cell (APC) or tumor cell surface to inhibit T cell activation. Blocking of the PD1/PD-L1 axis via anti-PD1 or anti-PD-L1 antibody prevents this inhibitory interaction and increases T cell activation and proliferation, enhancing tumor killing effect eventually. Reprinted with permission from Ref. 26. Copyright © 2020 Springer Nature Limited.