ABSTRACT
@#[Abstract] Objective: The co-culture model of LAG3+Jurkat cells and tumor cells was constructed to investigate the anti-tumor effect and mechanism of a novel fully human anti-LAG3 monoclonal antibody in vitro. Methods: Jurkat cells were stimulated with PHA to simulate TIL, and the secretion of IL-2 was detected by ELISA to evaluate the degree of Jurkat cell activation. Meanwhile, FCM, Immunofluorescence and WB assays were employed to detect the expression of LAG3 in activated Jurkat cells and MHC classⅡmolecule（MHC-Ⅱ）, a LAG3 ligand, in HGC-27, MGC-803 and A549 tumor cells. The co-culture model of activated LAG3+Jurkat cells and tumor cells was constructed, and CCK-8 assays were employed to detect the killing efficiency of LAG3+Jurkat cells against tumor cells at different effector-target ratios and the effect of the anti-LAG3 antibody . The secretion levels of cytokines IL-2, IL-10 and TNF-α in supernatant of co-culture system were detected by ELISA. Results: After 48 h treatment, 2 μg/mL PHA exhibited no obvious cytotoxicity to Jurkat cells (P>0.05), but could significantly induce IL-2 secretion (P<0.01) and LAG3 expression (P<0.01), indicating activated LAG3+Jurkat cells were acquired. MGC-803 and A549 cells significantly expressed MHC-Ⅱ (P<0.01), but HGC-27 cells did not express MHC-Ⅱ (P>0.05). The co-culture model of LAG3+Jurkat cells and tumor cells was constructed at a effector-target ratio of 10∶1. The anti-LAG3 antibody could effectively enhance the killing efficiency of Jurkat cells against MHC-Ⅱ+ tumor cells (P<0.05). Further analysis revealed that the secretion levels of cytokines IL-2, IL-10 and TNF-α were increased in the co-culture supernatant of MHC-Ⅱ+ target cell group (all P<0.01). Conclusion: A co-culture model of LAG3+Jurkat cells and tumor cells was successfully constructed in vitro. The anti-LAG3 antibody might increase the killing effect of Jurkat cells against MGC-803 and A549 tumor cells through blocking LAG3/MHC-Ⅱ interaction, which may be related to the increased secretion levels of cytokines IL-2, IL-10 and TNF-α in the supernatant of co-culture system.