Monocytes

Monocytes are circulating white blood cells (agranulocytes) that serve as precursors for macrophages and dendritic cells. Produced in the bone marrow, they patrol the bloodstream for several days before migrating into tissues in response to inflammatory signals. In tissues, they differentiate into macrophages or dendritic cells. In blood, they can phagocytose pathogens and present antigens, acting as a bridge between innate and adaptive immunity.