Abstract： Objective To investigate the effects of glioma microenvironment and COX-2 inhibitor celecoxib on the phenotypes and function of dendritic cell (DC).Methods The expression of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) production were detected in glioma C6 cells treated with different concentration of celecoxib.Monocytes were isolated from human peripheral blood and cultured with 200 ng/ml rhGM-CSF and 50 ng/ml rhIL-4,either C6 tumor cells supernatant (TSN) or TSN from C6 cells treated with celecoxib to generate DCs.Cell morphology was observed.Cell phenotype including CD1a,CD80,CD83 and D86 were analyzed on a FACScan.Production of IL-12 in DC supernatant and the potential to stmiulate allogeneic T cell proliferation were detected.Results The expression of COX-2 and PGE2 production in C6 cells decreased after treated with celecoxib in a concentration dependant manner.Typical DCs were induced in all groups and the expression of CD1a ((75.56±2.40)％,(75.09±3.67)％,(76.03 ±3.43)％),CD83((72.04±3.45)％,(71.44±3.78)％,( 73.63 ± 3.31 ) ％ ) had no difference (P ＞ 0.05 ).Expression of CD80 ( ( 58.41 ± 3.85 ) ％ ),CD86 ( ( 58.22 ±3.25)％ ) in DC with TSN obviously decreased compared with normal group( (70.36 ± 2.91 )％,(69.31 ±4.29 ) ％,P ＜ 0.01 ) as well as the IL-12 production ( ( 137.88 ± 5.33 ) pg/ml,( 186.04 ± 4.76 ) pg/ml) and the potential to stmiulate allogeneic T cell proliferation ( P ＜ 0.01 ).Celecoxib increased the expression of CD80,CD86 (66.83 ± 2.51,63.51 ± 5.47,P＜ 0.01 ) in DC and the same as IL-12 production( ( 170.31 ± 3.46) pg/ml,P ＜ 0.01 ) and the potential to stmiulate allogeneic T cell proliferation ( P ＜ 0.01 ),which were lower than the normal level.Conclusion Glioma microenvironment may induce the celecoxib can inhibit the expression of COX-2 and PGE2 in gliomas cells and improve the phenotypes and function defect of DCs.