Well a lot of the T cells will enter the bloodstream in order to spread through the body. My knowledge of this is fairly limited but chemokines serve as the nav

Well a lot of the T cells will enter the bloodstream in order to spread through the body. My knowledge of this is fairly limited but chemokines serve as the navigation instruments in many cases: a site of inflammation or infection will have immune cells expressing these signaling molecules that will slowly diffuse and create a gradient. T cells (for example) will follow this gradient to get to the site of interest (the process is called chemotaxis). No book recommendations off the top of my head, but I’ll post back if something comes up.