Human Programmed Cell Death Protein 1 Ligand 2 (PDCD1LG2) Protein

Background

Programmed cell death 1 ligand 2 (PDCD1LG2), commonly referred to as PD-L2, is an immune regulatory protein that belongs to the B7 family of immune checkpoint ligands. PD-L2 functions as a ligand for PD-1 (Programmed Cell Death Protein 1), an inhibitory receptor on T cells, and contributes to the modulation of immune responses by promoting T cell inhibition. This ligand is highly relevant in immune tolerance, particularly in peripheral tissues where it helps prevent excessive immune reactions that could lead to tissue damage. PD-L2, together with its better-known counterpart PD-L1, plays a key role in immune escape mechanisms in cancers, where it inhibits T cell activation and proliferation, enabling tumor cells to evade immune surveillance. PD-L2 is selectively expressed on antigen-presenting cells (APCs) such as dendritic cells (DCs), macrophages, and B cells. Its expression is inducible, being upregulated under conditions of inflammation or during immune activation through signals like interleukin-4 (IL-4) and interferon-gamma (IFN-γ). This selective and inducible expression of PD-L2 suggests it has specialized roles in fine-tuning immune responses, distinguishing it from PD-L1, which is more broadly expressed across various cell types, including non-immune cells.