T helper cell
PD-L2 binds to its receptor PD-1 with dissociation constant Kd of 11.3 nM. Binding to PD-1 can activate pathways inhibiting TCR/BCR-mediated immune cell activation (for a more detailed discussion see PD-1 signaling). PD-L2 plays an important role in immune tolerance and autoimmunity. Both PD-L1 and PD-L2 can inhibit T cell proliferation and inflammatory cytokine production. Blocking PD-L2 has been shown to exacerbate experimental autoimmune encephalomyelitis. Unlike PD-L1, PD-L2 has been shown activate the immune system. PD-L2 triggers IL-12 production in murine dendritic cells leading to T cell activation. Others have shown that treatment with PD-L2 Ig led to T helper cell proliferation.