Regulation of margination of inflammatory monocytes in the bone marrow vasculature by CX3CR1. (A) Under steady-state conditions, inflammatory monocytes are attached to the endothelial surface within the bone marrow vasculature, a response partly dependent on CX3CR1. Upon induction of peritoneal inflammation, inflammatory monocytes undergo demargination and are rapidly released into the circulation, resulting in increased numbers in the circulation. This facilitates their recruitment to the peripheral site of inflammation via adhesion and transmigration in the microvasculature at the affected site. (B) Under conditions where CX3CR1 is inhibited or absent, the number of monocytes released into the circulation is greater, as is the level of monocyte recruitment to the periphery. Professional illustration by Patrick Lane, ScEYEnce Studios.