Phagocytic leucocytes are attracted to the site of bacterial infection by chemotaxis. They adhere to the surface of capillary endothelial cells by interacting with cell adhesion molecules, termed margination, and use these molecules to move through the capillary walls, diapedesis. Intracellular killing is due to enzymes from granules which fuse with the phagocytic vacuole, and from a respiratory burst which produces products toxic to bacteria.