Animation showing an effector T cell (grey rounded cell) arriving at the site of infection (skin wound) where it amplifies the immune response. Pathogens (brown) have entered the wound and invaded the local area. The T cell releases cytokines (red dots) which cause a macrophage (large purple cell) to move towards the infected area by chemotaxis. This macrophage adheres to a pathogenic particle and forms pseudopods which engulf it. The engulfed particle will then be broken down and destroyed. This type of effector T cell is called a Helper T cell.