Programmed death ligand 2 (PD-L2, also known as CD273/B7-DC), a member of B7 family was identified among a library of genes differentially expressed between DCs and activated m acrophages. PD-L2 is a ligand for programmed death 1 (PD-1) which belongs to the CD28/CTLA-4 subfamily. Engagement of PD-1 by PD-L2 dramatically inhibits T cell receptor (TCR)-mediated proliferation and cytokine production by CD4 + T cells. At low antigen concentrations, PD-L2-PD-1 interactions inhibit strong B7-CD28 signals. In contrast, at high antigen concentrations, PD-L2-PD-1 interactions reduce cytokine production but do not inhibit T cell proliferation.Synonyms: B7DC, PD-1-ligand 2, PD-L2, PDCD1 ligand 2, PDCD1L2, PDCD1LG2, Programmed cell death 1 ligand 2, Programmed death ligand 2