| Background : Leukocyte-endothelial adhesive interactions
are important in inflammation. The human promyelocytic cell line
HL60 has been used for studies on the mechanisms of leukocyte-endothelial
interactions. In this study, I investigated the adhesive interactions
of HL60 cells with vascular endothelium, during dimethylsulfoxide
(DMSO)-induced granulocytic differentiation.
Methods : HL60 cells were incubated in the presence of DMSO for 72hours to induce granulocytic differentiation. The adhesion assay of HL60 cells to cytokine activated (IL-1£], 10U/ml, 4hrs) human umbilical vein endothelial cells (HUVEC) were carried out under non-static assay conditions. The expression pattern of adhesion molecules on HL60 cells after granulocytic differentiation was documented by flow cytometric analysis and Western blotting analysis. mRNA expression levels are detected by RT-PCR. Results :Undifferentiated HL60 (uHL60) are able to adhere to cytokine activated HUVEC under non-static assay conditions. Granulocytic differentiation of HL60 cells (dHL60) significantly enhanced their adhesion to activated HUVEC. Preincubation of HUVEC with an anti-E-selectin monoclonal antibody, H18/7, blocked this enhanced HL60 adhesion. Incubation of HL60 cells with a monoclonal antibody against sialyl lewis X (sLx), a carbohydrate ligand of E-selectin, also blocked adhesion. Flow cytometric analysis of HL60 cells revealed the increased sLx expression after granulocytic differentiation. Western blotting analysis of HL60 using anti-sLx mAb revealed components (MW 220kD and 140kD) during differentiaiton. I also observed an increased mRNA level for type VII fucosyltransferase (FucT-VII), one of key enzymes involved in sLx synthesis during granulocytic differentiation. Conclusions : Granulocytic differentiation of HL60 cells enhances adhesion to activated endothelial cells predominantly via an E-selectin-dependent interaction with sLx-containing structures. Further study may elucidate the regulation of selectin mediated leukocyte-endothelial interactions.(J Intern Med Taiwan 1998;9:131-141) |