generate 5 bullet points with the most important information from this text: Macrophages are a key player in the immune system, serving as a first line of defense against invading pathogens. They are a type of white blood cell that act as scavengers, engulfing and destroying foreign particles and dead cells. They also play a critical role in coordinating the immune response, communicating with other immune cells and releasing chemical signals to recruit them to the site of infection or injury.

Macrophages are derived from monocytes, a type of circulating immune cell that matures into a macrophage when it migrates to tissues. Once in the tissues, macrophages take on a variety of functions depending on the needs of the immune system. They can stimulate inflammation to help clear infections, or help to heal damaged tissues by releasing growth factors and promoting the formation of new blood vessels.

Despite their importance in the immune system, macrophages can also contribute to certain diseases when they become overactive or are unable to clear invading pathogens. Researchers are currently investigating ways to regulate macrophage activity in order to develop new treatments for diseases such as cancer, autoimmune disorders, and infectious diseases.

Overall, macrophages play a crucial role in the immune system, and understanding their function and behavior is essential for developing new therapies to fight disease.