The effects of Castanospermine, an oligosaccharide processing inhibitor, on mononuclear/endothelial cell binding and the expression of cell adhesion molecules

Abstract

Introduction: In this study we aimed to determine whether Castanospermine, a transplant immunosuppressive agent, impaired mononuclear/endothelial cell binding and expression of their cell adhesion molecules. Methods: The binding of human umbilical vein endothelial cells with peripheral blood mononuclear cells was measured by a binding assay using Chromium 51 label; the membrane expression of cell adhesion molecules was measured by flow cytometry expressed as mean fluorescence intensity ratios. Results: Castanospermine decreased mononuclear/endothelial cell binding if and only if both cell types were treated with Castanospermine: this impairment occurred if endothelial cells were treated with a range of doses of Castanospermine and mononuclear cells were treated with a constant dose of Castanospermine (p < 0.001 versus untreated p = 0.978) or vice versa (p = 0.004 versus untreated p = 0.582). Upon human umbilical vein endothelial cells Castanospermine reduced the mean fluorescence intensity ratios of E-selectin (p = 0.003), ICAM-1 (p < 0.001), ICAM-2 (p = 0.004) and PECAM-1 (p < 0.001) but increased it for P-selectin (p < 0.001). Upon peripheral blood mononuclear cells Castanospermine reduced the mean fluorescence intensity ratios of L-selectin (P < 0.001), LFA-1α (p < 0.001), VLA-4 (p < 0.001), Mac-1 (P < 0.001) and CR4 (p < 0.001) but increased the mean fluorescence intensity ratios of PSGL-1 (p < 0.001) and PECAM-1 (p = 0.001). Similar changes in mean fluorescence intensity ratios were found in the subset of lymphocytes and monocytes but the reductions in LFA-1α and VLA-4 on lymphocytes and Mac-1 and CR4 on monocytes were greater. Conclusions: The reduction in mononuclear/endothelial cell binding mediated by CAST and the reduction in expression of multiple cell adhesion molecules on these cell types help to explain the mechanism of its established immunosuppressive effect. Show more