In 1982, researchers put forward the concept of the CDw14 molecule (w stands for workshop, workshop) at the first white blood cell typing seminar in Paris, and then researchers conducted extensive research on the function of the CDw14 molecule and officially named the CD14 molecule in 1989. CD14 antigen is one of the key molecules in the process of immune response of the body. It participates in the natural defense response of the host and belongs to the pattern recognition receptor (PRR) family. It lacks ligand specificity and can bind to highly conserved common components of microorganisms.

CD14 can bind many microbial ligands, such as gram-negative bacteria LPS, mycobacterium lipoarabinomannan (LAM), spirochete lipoproteins, gram-positive bacteria lipoproteins, phosphoteichoic acid, and common components of the bacterial cell wall, such as peptidoglycan, apoptotic bodies, etc. CD14 can catalyze the binding of pathogens (such as gram-negative bacteria) and their products (endotoxin molecules) to receptors on cell membranes (such as Toll-like receptor 4, TLR4); It catalyzes the combination of lipoprotein and TLR2.

CD14 is highly expressed on the cell membrane of macrophages and neutrophils. For example, there are about 3000 on each neutrophil membrane, which can concentrate ligand molecules and participate in the receptor-ligand internalization process. Through internalization, it can not only activate the expression of cytokines but also participate in the degradation and detoxification effects of endotoxin molecules and other substances, such as internalizing endotoxin molecules into the endosomes and then transporting them to lysosomes. In neutrophils and macrophages, acyl acid hydrolase decomposes into deacyl lipid IV A, or dephosphorylation occurs under the action of phosphatase to produce lipid monophosphate IV A, Making endotoxin molecules lose toxicity.

CD14 can transfer the ligand to the corresponding receptor and exert the receptor-ligand binding effect, such as to TLR4, which will lead to endotoxin signal transduction and activate a series of enzymatic cascade reactions, so that TNF-a, IL-1, and IL-6 expressed. If the lipoprotein of gram-positive bacteria is transferred to TLR2, it can also induce the expression of cytokines such as IL-12. CD14 molecule not only participates in the clearance of endotoxin, but also in the activation of monocytes and macrophages. In addition, CD14 also participates in the clearance of apoptotic cells.