Phagocyte functions in response to bacterial infections. After sensing chemokines released by invading microorganism, leukocytes rapidly move toward the site of infection. This process involves initial changes in adhesive properties of the cells to the vessel endothelium followed by an extravasation step out of the blood vessel and directed migration into tissue. Once at the site of infection, cells phagocytize microbes and kill them by degranulation and reactive oxygen species (ROS) release.