Fig. 3
From: The biomarkers of hyperprogressive disease in PD-1/PD-L1 blockage therapy
PD-1 blockade significantly enhanced the proliferation and suppression activity of Treg cells: 1. Activated TCR and CD28 signaling enhances Treg cell proliferation and suppression activity. 2. High CTLA-4 expression may recruit more Treg cells. 3. Inhibition of IL-2 release from tumor-reactive T-eff cells and rapid absorption through CD25. 4. Adenosine and indoleamine 2,3-dioxygenase (IDO) are upregulated. 5. IFN-γ is suppressed by Treg cells