IL-4 decreases IFN-gamma-induced endothelial ICAM-1 expression by a transcriptional mechanism.

Intercellular adhesion molecule-1 (ICAM-1, CD54) is a cell surface ligand for LFA-1 (CD11a/18). Several cytokines, such as IL-1, TNF-alpha or IFN-gamma, have been shown to increase the ICAM-1 expression on cultured endothelial cells. Here we show that IL-4 decreases the IFN-gamma-induced ICAM-1 expression on an endothelial cell line (EA.hy 926), whereas IL-4 alone has practically no effects on ICAM-1 expression. The down-regulative effect was also seen at the mRNA level suggesting that this regulation process is transcriptional. At the same time IL-4 was unable to alter the TNF-alpha-induced ICAM-1 up-regulation. Both IFN-gamma and TNF-alpha are able to decrease the proliferation of the endothelial cell line, but IL-4 could not modify this response when added together with the other cytokines. Taken together we show in this paper that IL-4 decreases IFN-gamma but not TNF-alpha-induced up-regulation of ICAM-1 expression on EA.hy 926 cells.