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. 2023 Feb 23;14:1130438. doi: 10.3389/fimmu.2023.1130438

Figure 1.

Figure 1

Pharmacological mechanism of ICIs. APCs present MHC molecular complexes to TCR on T cells and activate T cells. CD4+ T cells secrete cytokines and stimulate CD8+ T cells proliferation. Activated CD8+ T cells kill tumor cells precisely. Normally, PD-L1 binds to PD-1, FGL-1 binds to LAG-3, inactivating CD8+ T cells and leading to autoimmune tolerance. After immunoediting, tumor cells express PD-L1 and FGL-1 and T cells express CTLA-4 and LAG-3, receptors on T cells bound with ligands on tumor cells or APCs, which will inactivate T cells. ICIs devitalized the PD-1/PD-L1, LAG-3/FGL-1 and CTLA-4/B7 signals and reactivated T cells to kill tumor cells.