Fig. 1
From: PD-1 and LAG-3: synergistic fostering of T cell exhaustion
PD-1 and LAG-3 play different roles in inhibiting T cell activation in exhausted T cells. a In effector CD8+ T cells, stimulation of the TCR and co-receptors (not shown) leads to the proliferation of the cells and the execution of effector programs, such as the secretion of cytokines and the killing of infected cells or tumor cells. This leads to the control of the infection and cancer. b Exhausted CD8+ T cells are characterized by the expression of inhibitory receptors, such as PD-1 and LAG-3. Signaling by PD-1 specifically reduces TCR- and co-receptor-induced proliferation. Complementary, signals by LAG-3 diminish the production of cytokines and the killing of target cells. Thus, the CD8+ T cell does neither proliferate nor get activated, therefore preventing to harm healthy tissues
