- Reticuloendothelial System (RES) also known as the mononuclear phagocyte system (MPS), the RES is a network of cells and tissues crucial for immune defense, homeostasis, and waste clearance.
- Composed primarily of phagocytic cells specialized in engulfing and digesting foreign particles, pathogens, and cellular debris.
Main Cell Types
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Monocytes
- Large white blood cells from the bone marrow.
- Differentiate into macrophages or dendritic cells in tissues.
Macrophages
- Tissue-resident phagocytes derived from monocytes.
- Found in liver (Kupffer cells), lungs (alveolar macrophages), brain (microglia), and connective tissues (histiocytes).
- Key functions: pathogen engulfment, cytokine release, and immune response coordination.
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Dendritic Cells
- Antigen-presenting cells originating from monocytes or bone marrow progenitors.
- Located in skin, lungs, and gastrointestinal tract.
- Crucial for initiating adaptive immune responses by presenting antigens to T cells.
Neutrophils
- Abundant white blood cells with phagocytic abilities, mainly involved in innate immunity, especially against bacterial infections.
- Not traditionally considered part of the RES.
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Functions of the Reticuloendothelial System (RES)
- Immune Defense: Engulfs and destroys pathogens (bacteria, viruses, parasites).
- Debris Clearance: Maintains homeostasis by removing damaged cells and waste.
- Antigen Presentation: Dendritic cells process and present antigens to T cells, triggering adaptive immunity.
- Inflammation Regulation: Modulates inflammation via cytokine production and response.
- Iron Recycling: Macrophages, particularly in the spleen, recycle iron from red blood cells.
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