Any mononuclear, actively phagocytic cell arising from monocytic stem cells in the bone marrow; these cells are widely distributed in the body and vary in morphology and motility, although most are large, long-lived cells with nearly round nuclei and abundant endocytic vacuoles, endosomes, lysosomes, and phagolysosomes. Phagocytic activity is typically mediated by serum recognition factors, including certain immunoglobulins and components of the complement system, but also may be nonspecific for some inert materials and bacteria, as in the case of alveolar macrophages; macrophages also are involved in cell-mediated immune responses, participate in presenting antigens to lymphocytes, secrete a variety of immunoregulatory molecules, and interact with natural killer cells.
[macro- + G. phago, to eat]
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Examples: glitazone, GI cocktail, etc.