What is Macrophage?

Macrophages are a type of white blood cell that play an important role in the human immune system and carry out various functions including engulfing and digesting microorganisms; clearing out debris and dead cells; and stimulating other cells involved in immune function. Macrophages confer innate immunity, which is typically the first line of defense against foreign antigens.In addition to having an immune role, macrophages also secrete anti-inflammatory cytokines and help mediate reparative processes. Macrophages form from monocytes, which themselves derive from the bone marrow. Monocytes circulate through the blood for one to three days before migrating into tissues, where they become macrophages or dendritic cells. Macrophages can be found within many organs in the body, including the liver, brain, bones, and lungs, as well as in the blood, particularly at sites of infection. Macrophages can largely be categorized into two main types: M1 and M2 macrophages. The M1 type, referred to as classically-activated macrophages, are activated by pathogen invasion and play a large role in the immune response to foreign pathogens such as bacteria. The M2 type, referred to as alternatively-activated macrophages, play a role in wound healing and tissue repair, and have an anti-inflammatory role. Dr. Fernando Martinez Estrada from the University of Surrey has opened up a whole new area of study into how macrophages work and how they get activated. Their method is based on the colony-stimulating factor 1 receptor (CSF1R), which makes it possible to accurately identify the types of macrophage cells in both tissue and blood.