macrophage

a large scavenger cell (a PHAGOCYTE ) present in connective tissue and many major organs and tissues, including the bone marrow, spleen, LYMPH NODE , liver (see KUPFFER CELLS ), and the central nervous system (see MICROGLIA ). They are closely related to MONOCYTE .Fixed macrophages (histiocytes) are stationary within connective tissue; free macrophages wander between cells and aggregate at focal sites of infection, where they remove bacteria or other foreign bodies from blood or tissues. See also RETICULOENDOTHELIAL SYSTEM .