Macrophage activation refers to the process by which macrophages, a type of immune cell, become activated in response to signals from the immune system. This activation can occur in a variety of ways, such as in response to pathogens, inflammation, or other immune signals. Activated macrophages play a key role in the immune response by phagocytosing and destroying pathogens, secreting pro-inflammatory cytokines, and presenting antigens to other immune cells. Understanding how macrophages are activated and their role in the immune response is important for developing treatments for infectious diseases, autoimmune disorders, and cancer.