Previous studies with human umbilical vein endothelial cells (HUVEC) have shown that the cytokine IL-4 induces adherence of human eosinophils, but not neutrophils, because of its ability to selectively induce surface expression of vascular cell adhesion molecule-1 (VCAM-1). Because the cytokine IL-13 shares a number of biologic properties with IL-4, we examined the effect of IL-13 on the expression and function of adhesion molecules on HUVEC. Incubation of HUVEC for 4 to 48 h with IL-13 (0.1 to 15 U/ml) induced surface expression of VCAM-1, as detected by indirect immunofluorescence and flow cytometry, without significantly affecting expression of E-selectin or intercellular adhesion molecule-1. The kinetics and maximal IL-13-induced expression of VCAM-1 were similar to those seen with IL-4. Treatment of HUVEC with an optimal concentration of IL-13 (15 U/ml for 24 h) induced adhesiveness for eosinophils, but not for neutrophils, and adhesion was completely inhibited by mAb recognizing VCAM-1 or alpha 4 integrin (CD49d). These results demonstrate that IL-13, like IL-4, selectively stimulates HUVEC to express functional cell surface VCAM-1 and suggest a possible role for IL-13 in promoting VCAM-1/alpha 4 integrin-dependent accumulation of eosinophils during allergic and other inflammatory reactions in vivo.

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