– PD-1 ligand 2 (PD-L2) as a second ligand for PD-1 and compare the function and expression of PD-L1 and PD-L2. 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. PD-L2 Protein, Human, Recombinant (His & Avi) is expressed in HEK293 mammalian cells with C-His-Avi tag. The predicted molecular weight is 25.3 kDa and the accession number is Q9BQ51.