L-4F weakened the immunosuppressive function of MDSCs, resulting in decreased production of ROS and H2O2 by MDSCs, and increased T cell proliferation, interferon γ and tumor necrosis factor β secretion, and CD3+CD4+ T and CD3+CD8+ T cell infiltration into the mouse spleen and pancreatic cancer tissue. Here, CD4 is linked to familial pancreatic carcinoma.