Interleukin 4 amplifies monocyte chemotactic protein and interleukin 6 production by endothelial cells.

Upon exposure to interleukin 4 (IL-4), human umbilical vein endothelial cells (EC) produced low amounts of IL-6 and expressed low levels of IL-6 transcripts. While being a weak stimulus for IL-6 production, IL-4 amplified the release and mRNA expression of this cytokine in response to optimal concentrations of IL-1. IL-4 also induced low levels of monocyte chemotactic protein but amplified the expression of this chemoattractant in response to inflammatory signals. Thus IL-4, by amplifying at the level of the vascular endothelium the expression of vascular cell adhesion molecule 1 selectively, as well as that of chemoattractants and IL-6, may favour the selective recruitment and activation of lymphoid and monocytic elements crucial for subacute/chronic inflammation and immune reactions.