Macrophage Activation Syndrome

IMacrophages are important constituents of mononuclear phagocyte system, earlier known as reticulo-endothelial system. Tissue macrophages are innate immune cells with well-established roles in the primary response to pathogens, particularly abundant in capillary walls of lung (alveolar macrophages), Liver (Kupffer cells), spleen, brain, connective tissues, serous cavities (peritoneal macrophages) and bone marrow. In the case of cell mediated immunity, Macrophage activating response is a T-cell mediated phenomenon resulting in activation of macrophages, capable of killing and digesting microbes. The classically known macrophage activation is induced by IFN-γ, which triggers a harsh proinflammatory response that is required to kill intracellular pathogens.Macrophages also produce proinflammatory cytokines: IL-1, 8, 12, TNF-α, secrete plasmin, transferrin, and cause oxidative injuries, thus contributing to the pathogenesis of various acute and chronic diseases. Macrophages play important role in immune response and autoimmune phenomenon by removing immune complexes from the circulation.1