sCD14

sCD14, also known as soluble CD14, is a protein that plays a critical role in the immune system, particularly in the recognition of bacterial lipopolysaccharides (LPS). CD14 is a pattern recognition receptor primarily found on the surface of monocytes, macrophages, and certain other immune cells. When shed from the cell surface, it becomes soluble (sCD14), circulating freely in the blood and other bodily fluids.

The primary function of sCD14 is to facilitate immune responses to bacterial infections. It can bind LPS from gram-negative bacteria and transfer it to other immune receptors such as Toll-like receptor 4 (TLR4), triggering inflammatory signaling pathways. This process prompts the production of cytokines and other mediators necessary for pathogen clearance. sCD14 also interacts with other ligands and molecules, modulating immune activation beyond bacterial recognition.

sCD14 serves as an important biomarker for various inflammatory and infectious conditions. Elevated levels of soluble CD14 have been observed in diseases such as sepsis, HIV infection, and inflammatory bowel disease. Because of its role in immune activation, sCD14 levels can also reflect the state of immune system dysregulation or response.

The production of sCD14 can occur through shedding of membrane-bound CD14 or from alternative splicing of the CD14 gene. Its levels in serum are influenced by factors such as infection, inflammation, and immune status. Given its central role in innate immunity and inflammation, sCD14 is an area of interest for research into diagnostic and therapeutic strategies for infectious and inflammatory diseases.