PDAC and stromal-derived molecules Effects on T cells References Adressins (e.g. VCAM-1, CD62E, Mad CAM-1, CD166) Promote Treg transmigration to the PDAC microenvironment [33] αLβ2 integrin A reduced expression impairs CD8+ T cell infiltration [112] Galectin-1 Increases Th2 and decreases Th1 cytokines Induces CD4+and CD8+  T cell apoptosis [113,143] Induces IL-10 production in Treg L1CAM Reduces CD4+T cell proliferation [105] CCL2 Induces immunoregulatory DCs which in turn expand Treg [32] CCL5 More efficient Treg migration to PDAC site [31] CXCL12 Impedes T cells migration to the tumor site [21] TGFβ1 Induces Treg expansion [23,28-30,110,115] Inhibits CD4+ T cell proliferation and migration Induces Th17 IL-1β and IL-6 Induce Th17 [115] Fibroblast activation protein (FAP-α) Suppresses effector T cells [135] Indoleamine 2,3-dioxygenase (IDO) Induces Treg differentiation [22] Induces T cell arrest, anergy and death.

Table 1: Tumor and stromal cells derived molecules acting on T cells and involved in PDAC immunosuppression.