Abstract: AIM: To investigate the interaction of CD11b and its ligand ICAM-1 on PMN-HUVEC adhesion and their action mechanism. METHODS: Human neu-trophils were isolated from fresh heparinized blood of healthy volunteers by dextran sedimentation followed by Ficoll-Hypaque gradient centrifugation.The polymopho-nuclear leukocytes-human umbilical vein endothelial cells (HUVECs) were isolated from human umbilical veins by 0.25%trypsin and then cultured in RPMI1640.There were five groups in this experiment for the adhesion as-say :control group, LPS treated group (PMNs and HU-VECs were stimulated with 100 μg°L^-1 LPS in different time), CD11bMoAb pretreated group, ICAM-1 MoAb pretreated group, combined CD11b and ICAM-1 MoAb pretreated group.The rate of PMN-HUVEC adhesion was calculated as formula after radiolabelling PMNs with ^99mTc-HM-PAO.adherence(%) =cpm lysate/cpm added ×100.RESULTS: PMN-HUVEC adhesiveness in-creased after stimulated for 15 min compared with that in the control group (37.45%±3.92% vs 11.03% ± 4.15% P<0.05), and it reached the peak after 4 hours (73.50%±6.39%). MoAb to CD11b and ICAM-1 sig-nificantly inhibited this adhesiveness (P<0.05). More-over, an additive effect was observed when two MoAbs were used together (P< 0.05). CONCLUSION: CD11b and ICAM-1 play a crucial role in the course of PMN-HUVEC adhesion, and the adhesiveness between cells is significantly attenuated after MoAb blocked the action of adhesion molecules.

Key words: polymophonuclear leukocytes, human umbilical vein endothelial cell, CD11b, ICAM-1, adhe-sion, LPS, monoclone antibody