The inflammatory response in the CNS.

In recent years it has been recognized that cells of the mononuclear phagocyte lineage, macrophages and microglia, are a major component of gliosis. We review here studies on the kinetics of the myelomonocytic response to acute excitotoxin induced neuronal degeneration and following the injection of endotoxin (LPS) into the parenchyma of the central nervous system. These studies have shown that the kinetics of myelomonocytic recruitment to the parenchyma of the central nervous system is quite unlike that of other tissues; the polymorphonuclear cells are largely excluded and monocytes are only recruited after a delay of several days. The unusual nature of the inflammatory response in the central nervous system needs to be considered when drawing parallels with the acute inflammatory response in other tissues.