CD14
- OMIM: 158120
- UniProt: P08571
CD14 ( "CD" cluster of differentiation ) is a surface protein which is formed mainly by monocytes and macrophages of mammals. CD14 has opsonin receptor function and binds bacterial fatty acids and peptidoglycans. Together with TLR4 and lymphocyte antigen 96 it forms the lipopolysaccharide receptor.
CD14 is a 55 kDa large glycoprotein which is connected via a glycosylphosphatidylinositol anchor to the cell membrane. In endothelial cells CD14 has a regulatory function for cell survival. Although predominantly in much lower concentrations, the dissolution of CD14 in these cells by macrophages leads to programmed cell death (apoptosis).
CD14 is also expressed in cells of the brain: It is found under basal conditions ( especially in the microglia ) in the leptomeninges, choroid plexus, and along the blood vessels. If lipopolysaccharides be administered systemically (intravenously), CD14 is in these regions over the next (1 ) -3 - formed (24) hours increased. This activation begins in the structures with a more permeable blood -brain barrier, the ( circumventrikulären organs) and continues into deeper parts of the brain.
Polymorphisms
Mutations in the CD14 gene have been found in many studies. Thus, in a study of 440 Han Chinese children the incidence of juvenile idiopathic arthritis was directly associated with the C- 159T polymorphism. The same mutation presented in a study of 170 Greek children is a risk factor for Hodgkin lymphoma represents a possible increased risk of COPD was found in the study of 250 smokers.
Another mutation C- 260T is associated with the severity of the course of infectious diseases such as periodontitis, or ulcerative colitis.
Regulation
The CD14 expression by TNF- α and is IL- 1β enhanced ( in the sense of positive feedback ) as long as lipopolysaccharides are ( differently in different tissues ) present.