ObjectiveTo study the effect of tumor associated neutrophil (TAN) releasing a proliferation-inducing ligand (APRIL) on the proliferation of pancreatic cancer cells in microenvironment.Methods① The expressions of APRIL in neutrophils (differentiated by HL-60 cell) and TAN cells were detected by use ELISA. ② The expressions of APRIL receptors B cell maturation antigen (BCMA) and trans-membrane activator and CAML interactor (TACI) in pancreatic cancer cell line PANC-1 were confirmed by use Western blotting. ③ Pancreatic cancer PANC-1 cells were co-cultured with TAN, and divided into a PANC-1 control group (referred to as the control group), a PANC-1+TAN treatment group (referred to as the PANC-1+TAN group), PANC-1+TAN+APRIL antibody treatment group (referred to as PANC-1+TAN+APRIL group), and PANC-1+rtificial recombinant APRIL protein (rAPRIL) treatment group (referred to as PANC-1+rAPRIL group). The CCK8 method was used to determine TAN release of APRIL on PANC-1 effect of cell proliferation activity.Results① The APRIL content in the culture medium of TAN cell group was higher than that of neutrophil group [(556.20±84.38) pg/mL vs. (377.17±57.07) pg/mL, P=0.038]. ② PANC-1 cells express the receptors BCMA and TACI of APRIL. ③ PANC-1 cell activity of PANC-1+TAN group and PANC-1+rAPRIL group [(126.80±1.42)%, (168.95±12.54)%] were significantly higher than the control group [(100 ± 0.00)%, P<0.05, P<0.001], the activity of PANC-1 cells in the PANC-1+TAN group was significantly higher than that in the PANC-1+TAN+APRIL group [(86.29 ± 12.20)%, P=0.003] and significantly lower than that of PANC-1+rAPRIL group (P=0.002), the activity of PANC-1 cells in PANC-1+rAPRIL group was significantly higher than that in PANC-1+TAN+APRIL antibody group (P<0.001).ConclusionIn the microenvironment of pancreatic cancer, the release of APRIL from TAN increases, which promotes the proliferative activity of PANC-1 in pancreatic cancer cells, which provides a new idea for the mechanism research and treatment of pancreatic cancer progression.