Phagophage cell
System), also known as mononuclear phagocyte system, is a cell system composed of macrophages with strong phagocytic ability and their precursor cells in higher animals, and is an important part of the body's defense structure.
The cells of mononuclear phagocyte system include directional stem cells, monocytes, young monocytes in bone marrow, monocytes in blood and macrophages in various organs. The latter includes macrophages of connective tissue, kupffer cells of liver, dust cells of lung, macrophages of lymph nodes and spleen, macrophages of pleural cavity and peritoneum, microglia of nerve tissue and osteoclasts of bone tissue. They are all derived from mononuclear cells in the blood, with a single nucleus, and receptors for antibodies and complements on the surface of the cell membrane, and their phagocytosis is active.
The function of mononuclear phagocyte system, macrophages not only phagocytize and remove foreign bodies and aging cells, but also play an important role in immune response: they are the main antigen presenting cells, and in the initial stage of immune response, macrophages can capture and process antigens, and they can retain the most characteristic molecular genes of antigens (antigenic determinants) and combine with MHC-II molecules of macrophages themselves to form antigen peptide -MHC molecular complexes.
appear
Cells,
APC)； In the effective stage of immune response, it can gather around the focus and become an important component to destroy target cells and phagocytize bacteria. In addition, the system has the function of secreting a variety of bioactive substances (such as lysozyme, complement, tumor growth inhibitory factor).