Author: V. Dimov, M.D.
Reviewer: S. Randhawa, M.D.

Monocytes are CD45+ CD14+ cells. Granulocytes are CD45+ CD15+ cells.

CD14 is a component of the innate immune system.

It exists in 2 forms:

- anchored into the membrane by a glycosylphosphatidylinositol (GPI anchor) tail (mCD14)
- soluble form (sCD14)

Our innate immune system recognizes LPS via the LPS signal transduction pathway, which has the trimolecular complex of CD14/TLR4/MD2 at the core. CD14 was the first described pattern recognition receptor (PAMP receptor).


TLR4 and
CD14 recongnize LPS

In the initial stages of an immune response, the innate immune system recognizes the presence of pathogens and provides the first line of defense. This video is from: Janeway's Immunobiology, 7th Edition Murphy, Travers, & Walport. Source: Garland Science.

Signaling pathway of toll-like receptors. Dashed grey lines represent unknown associations. Image source: Wikipedia.

CD14 acts as a co-receptor (along with the toll-like receptor TLR 4 and MD-2) for the detection of bacterial lipopolysaccharide (LPS).

CD14 can only bind LPS in the presence of lipopolysaccharide-binding protein (LBP).

CD14 is expressed mainly by macrophages and (at 10 times lesser extent) by neutrophil granulocytes. It is also expressed by dendritic cells.

SNPs associated with atopic diseases

Filaggrin gene
Filaggrin is essential for epidermal barrier function. SNP associated with eczema and asthma.

17q12-21 gene
ORMDL3 protein defects associated with asthma.

5q22-32 gene
CD14 is a lipopolysaccharide (LPS) receptor. SNPs associated with asthma and atopy.

3p21-22 gene
CCR5 is a chemokine receptor. SNP can be protective against asthma.

Xp22 gene
TLR7 and TLR8 are recognition receptors for viral ssRNA. SNPs assciated with asthma, rhinitis, atopic dermatitis.

5q31 gene
IL-13 is a cytokine that induces IgE secretion, mucus production, and collagen synthesis (fibrosis). SNPs associated with asthma.

ADRB2 gene
ADRB2 gene encodes β2-adrenergic receptor. Argenteum (Arg) or Arg/Arg phenotype associated with decreased albuterol response compared to Gly/Gly phenotype at residue 16.

ADAM33 gene
Type 1 transmembrane protein involved in cell-to-cell interactions. SNPs associated with asthma.

Related reading

Asthma in African Americans: What can we do about the higher rates of disease? CCJM, 2012.
CD14, from Wikipedia, the free encyclopedia.

Published: 06/17/2009
Updated: 01/17/2012

No comments: