STUDIES OF THE MODULATION OF MHC ANTIGEN AND CELL-ADHESION MOLECULE EXPRESSION ON HUMAN DERMAL MICROVASCULAR ENDOTHELIAL-CELLS

Interactions between leukocytes and endothelial cells, particularly in the microvasculature, are important for the initiation and regulation of tissue inflammation. These interactions are regulated by the recognition of specific cell adhesion molecules (CAM) on both leukocytes and endothelial cells. In this study, we examined the modulation of cell surface expression of MHC antigens and the CAM intercellular adhesion molecule 1 (ICAM-1), lymphocyte function antigen 3 (LFA-3), and CD44 on human dermal microvascular endothelial cells (HDMEC) both grown in monolayers and differentiated into capillary-like structures on the basement membrane-like substrate matrigel. HDMEC grown in monolayers or differentiated on matrigel express comparable cell surface MHC class I, LFA-3, CD44, and ICAM-1. ICAM-1, but not LFA-3 or CD44, was increased in expression in a dose- and time-dependent manner by interleukin 1 (IL-1) alpha, tumor necrosis factor (TNF) alpha, lipopolysaccharide (LPS), or interferon (IFN) gamma. Comparable upregulation was observed both in cells grown in monolayers and cells differentiated on matrigel. IL-1 alpha, TNF alpha, and LPS increased ICAM-1 expression on average 100-200% whereas IFN gamma was somewhat less potent. Comparative studies with human umbilical vein endothelial cells (HUVEC) demonstrated consistently lower levels of ICAM-1 expression on HUVEC, but greater increases after cytokine stimulation. Pretreatment with dexamethasone or transforming growth factor (TGF) beta did not affect baseline expression of ICAM-1 or inhibit upregulation of ICAM-1 on HDMEC by IL-1 alpha, TNF alpha, LPS, or IFN gamma. Both IFN gamma and TNF alpha, but not IL-1 alpha increased MHC class I expression, whereas only IFN gamma induced the expression of HLA-DR on HDMEC. The effect of IL-1 alpha, TNF alpha, or IFN gamma was inhibited by antibody to the specific cytokine, but was unaffected by antibody to other cytokines. Additionally, IFN alpha or beta inhibited upregulation of HLA-DR by IFN gamma, but had no effect on the increased MHC class I or ICAM-1 expression mediated by this cytokine. These data demonstrate that the expression of CAM and MHC antigens on small vessel-derived endothelial cells is different from that observed on large-vessel HUVEC, is regulated by the presence of multiple cytokines operating via distinct pathways, and the expression and regulation of these proteins appear to be similar on cells that have been grown in monolayers to those morphologically differentiated into blood vessel-like structures.