FIGURE 1.

Molecular mechanism of PD‐1/PD‐L1 blocker action.PD‐1/PD‐L1. After PD‐1/PD‐L1 conjugation, the ITIM and ITSM structures in the PD‐1 cell membrane region were phosphorylated, and phosphatase SHP‐2 was recruited to the cell membrane region, so that the TCR and CD28 membrane domains were dephosphorylated, and the first signal and co‐stimulation signals of T cells were activated, which could not be transmitted to the downstream proteins, and the T cells could not be activated. When PD‐1 / PD‐L1 monoclonal antibody is activated, the intramembrane motif of PD‐1 cannot be phosphorylated, and SHP‐2 recruitment is lost. There is no phosphatase dephosphorylation, and the activation signals of TCR and CD28 can be transmitted to the downstream proteins, finally stimulating the proliferation and differentiation of T cells