Page 102 - Read Online

Page 280 Cencioni. Neuroimmunol Neuroinflammation 2020;7:277-90 I http://dx.doi.org/10.20517/2347-8659.2020.18

Figure 1. PD-1 inhibitor checkpoint regulates T cell activation during immune surveillance and induces T-cell exhaustion in cancer. (1)
PD-1 is expressed on activated T cells and regulates the activity of late differentiate effector cells. The foreign antigens are presented
to T cells by the TCR engagment with MHC expressed on dendritic cells, infected cells or tumor cells. Thus, T cells proliferate and
differentiate in effector and memory cells. Effector cells kill the foreign antigens express on infected or tumor cells by releasing
inflammatory cyokines and cytotoxic granules that induce target-cells to apoptosis. PD-1 is an inhibitory checkpoint able to regulate
the T cell activation when the inflammation is resolved. (2) After activation, PD-1 increases on T cells and the link with the ligand
PDL-1 reduces the T cell functionality. Thus, T cells are not able to kill the tumor or reduce the viral load and this condition called
T-cell exaustion favours a persistent infection and tumor spread. (3) The blocking of PD-1 with monoclonal antibodies restores T cell
function. T cells proliferate and differentiate in effector and memory cells contributing to resolve the infection or tumor. MHC: major
histocompatibility complex