IL-6, monocyte infiltration and parenchymal cells

The January issue of Trends in Immunology contained an interesting article by Kaplanski et al., in which the authors observed that interleukin-6 (IL-6) acts as a switch, regulating the transition from neutrophil to monocyte involvement during the inflammatory response [1]. In this model, activated polymorphonuclear (PMN) cells release soluble interleukin-6 receptor a (sIL-6Ra), which, upon binding of locally produced IL-6, combines with glycoprotein 130 (gp130) on endothelial cells, enabling them to switch from IL-8 (neutrophil-recruiting) to monocyte chemotactic protein-1 (monocyte-recruiting) secretion