So let's suppose we have some type of infection taking place, let's say a bacterial cell infects our tissue. Now as soon as that infection takes place the innate immune system will try to prevent that infection from spreading. It will try to localize that infection via the process of inflammation. And what inflammation does is it dilates our blood vessels. It brings more blood to that area and that brings specialized antigenpresenting cells known as macrophages. Now, what do macrophages actually do?