IL-6 could induce the expression of the receptor for IL-4 and augment the response to IL-4 in macrophages, but IL-6raΔmyel mice are resistant to IL-4-mediated M2 polarization and exhibit enhanced susceptibility to lipopolysaccharide (LPS)-induced endotoxemia [55]. Here, IL4 is linked to serum lipopolysaccharide activity.