Fig. 1
From: Targeting immune checkpoints in hematological malignancies
CTLA-4-mediated immune regulation. Schematic illustrating T cell-intrinsic (left) and extrinsic regulation by CTLA-4 (right). Left: CTLA-4 is upregulated on activated T cells and competes with the CD28 co-stimulatory receptor due to its higher affinity for CD80/CD86. Right: CTLA-4 plays a critical role in Treg-mediated immune regulation. The CTLA-4/CD80 interaction between Treg/APCs induces indoleamine 2,3-dioxygenase (IDO), a key enzyme that suppresses T cells by tryptophan deprivation. Additionally, Tregs down-modulate CD80/86 expression on APCs by transendocytosis