ABSTRACT
Macrophages are multifunctional cells. They play a key role in natural and acquired host defense reactions, in homeostasis, and in the regulation of numerous biological processes. Their main tools to achieve these goals are: phagocytosis followed by intracellular digestion and production and release of soluble mediators such as cytokines, chemokines, and nitric oxide. Macrophages can be found as resident cells in all organs of the body and they can be recruited to sites of inflammation. Their immediate precursors are monocytes, which are released in the blood circulation from the bone marrow. After some time, monocytes leave the circulation, cross the barrier formed by the walls of blood vessels, and enter into one of the organs where their final differentiation into mature macrophages will take place.
