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. 2020 Aug 22;33(1):27–37. doi: 10.1093/intimm/dxaa057

Fig. 1.

Fig. 1.

CD8 T-cell exhaustion model in chronic antigen stimulation. (A) At the peak of the T-cell response during acute antigen stimulation, responding CD8 T cells differentiate into a heterogenous effector pool composed of terminal effector and memory precursor cells. Upon antigen clearance, terminal effectors undergo cell death, while memory precursors survive and become functional memory cells. (B) Under chronic antigen stimulation, responding CD8 T cells differentiate into two subsets of PD-1-expressing exhausted CD8 T cells. The stem-like CD8 T-cell (green) maintains self-renewal and proliferative potential helping to sustain the pool of antigen-specific CD8 T cells. Stem-like cells also give rise to terminally differentiated (red) CD8 T cells which contribute to antigen (viral or tumor) control and progressively lose cytolytic function resulting in cell death. (C) Responding CD8 T-cell populations differ in phenotype and function during acute and chronic antigen stimulation.