IL-4 regulates the morphology, cytoskeleton, and proliferation of human umbilical vein endothelial cells: relationship between vimentin and CD23.

Many of the vascular endothelial changes associated with inflammation can be induced in vitro by the cytokines tumour necrosis factor, IL-1, and IFN gamma. On the other hand, although IL-4 is a powerful mediator of leucocyte function, its influence on endothelial cells has not yet been fully determined. In this study the effect of IL-4 on human umbilical vein endothelial cells has been investigated. It is shown that IL-4 stimulates DNA synthesis over the first 24 h in culture, followed by dramatic alterations in endothelial cell morphology in which the cobblestone appearance of cells grown to confluence in medium changes to a monolayer composed of islands of tightly packed polygonal cells. The morphological changes induced by IL-4 were accompanied by a reorganization of the intracellular vimentin matrix from a diffuse pattern to a perinuclear concentration observed by staining with vimentin antibodies. Similar patterns of vimentin staining were also observed with an antibody to the low affinity IgE receptor (CD23) normally associated with IL-4 activation of B lymphocytes. Our results suggest that this represents cross reactivity between CD23 and vimentin rather than the appearance of CD23 in endothelial cells. Amino acid sequence comparison between CD23 and vimentin indicated significant homology between these two molecules, including a leucine zipper-like motif. Our results suggest that IL-4 may be an important regulator of endothelial cell morphology and function in inflammation.