PDCD1LG2 and neoplasm: Furthermore, PD-L2 expression was identified in a variety of tumor types even in the absence of PD-L1 expression,16 and a recent study revealed the presence of PD-L2 specific T-lymphocytes able to recognize their targets expressed by either tumor or immune cells and able to induce the release of Th-1 cytokines, like IFN-γ and Tumor Necrosis Factor-alpha (TNF-α).