A Cytoscape network diagram in our study showed that PD-L2 in PDAC is closely related to the expression of PD-L1, CD86, TNFRSF14, PD-1, CD160 and CTLA-4, which are important for the regulation of immunodeficiency and autoimmune diseases [36]. The gene discussed is PDCD1LG2; the disease is immunodeficiency disease.