Reticuloendothelial system is part of the immune system of human body and consists of phagocytic cells. It is closely related to lymphatic system because the two are independent structurally and functionally. This system is made up of highly phagocytic cells which are widely distributed in the body. These cells include:
- Macrophages of connective tissue, reticular tissue and lungs
- Monocytes of blood
- Kupffer’s cells of liver
- Meningocytes of meninges
- Microglial cells of nervous tissue
- Foreign body giant cells.
The endothelial cells, fibroblasts, and most leukocytes arc not included in this system because of their poor power of phagocytosis.
Functions of Reticuloendothelial system:
1. The system forms first line of defense of the body against microorganisms, because of the amoeboid and phagocytic properties of its cells.
2. The macrophages of lymphoid tissue are now considered to be intimately concerned with mounting specific immune responses by the neighboring cells.
3. Many of the prominent sites of RES are also important sites of hemopoiesis.