CD14

CD14 is a pattern recognition receptor primarily expressed on the surface of monocytes, macrophages, and neutrophils. It plays a crucial role in the innate immune system by recognizing pathogen-associated molecular patterns, particularly bacterial lipopolysaccharides (LPS), which are components of the outer membrane of gram-negative bacteria. CD14 functions as a co-receptor in conjunction with Toll-like receptor 4 (TLR4) and MD-2, facilitating the detection and response to bacterial infection.

There are two forms of CD14: a membrane-bound form (mCD14) and a soluble form (sCD14). The membrane-bound form is anchored to the cell surface, while the soluble form circulates in the blood and other body fluids. sCD14 can aid in the detection of LPS even in cells lacking membrane CD14, expanding the immune response.

The binding of LPS to CD14 triggers a cascade of signaling events that activate inflammatory pathways, leading to cytokine production and the initiation of immune responses. This process is essential for the early defense against bacterial pathogens but can contribute to excessive inflammation if dysregulated, as observed in septic shock.

CD14 is encoded by the CD14 gene located on chromosome 5q31. It has been studied extensively as a biomarker for susceptibility to infections and inflammatory diseases. Variations in CD14 expression and function can influence individual immune responses, impacting disease outcomes.

Overall, CD14 is a key component of the innate immune system, mediating pathogen detection and initiating immune responses to bacterial infections, with implications for inflammatory regulation and disease susceptibility.