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Analyte: Intra-Cellular Adhesion Molecule-1
Specimen Type: Serum, EDTA Plasma, Inquire for additional option(s)
Optimum Volume: 0.5 mL
|3 days||16 months||1 year|
Reporting units: ng/mL
Biological or Clinical Significance:
Adhesion molecules mediate the interaction of cells with the extracellular matrix and with other cells. The immunoglobulin proteins contain a large class of adhesion molecules with, multiple immunoglobulin-like (Ig) domains. ICAM-1 (CD54) is a member of this family. It is a 90-kDa type-I transmembrane glycoprotein with five Ig-like extracellular domains. The most important ligands for ICAM-1 are the ß2 integrins LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18), which are expressed on leukocytes. ICAM-1 thus mediates the adhesion of leukocytes to ICAM-1-expressing cells. ICAM-1 also binds fibrinogen and hyaluronan among other ligands.
ICAM-1 is either a transmembrane protein (mICAM-1) or soluble (sICAM-1). mICAM-1 is expressed on endothelial and epithelial cells, lymphocytes, monocytes, eosinophils, keratinocytes, dendritic cells, hematopoietic stem cells, hepatocytes, and fibroblasts. Regulation of ICAM-1 expression is cell specific. Up-regulation generally is by inflammatory cytokines (TNF-α, IFN-7 and IL-1) and down-regulation generally is by anti-inflammatory agents (e.g. glucocorticoids). One important, well-characterized function of ICAM-1 is immune-cell trafficking. At sites of inflammation, inflammatory cytokines induce up-regulation of ICAM-1 expression on vascular endothelial cells and activation of leukocyte integrins. This leads to adhesion of leukocytes to the local endothelium, an essential step in migration of leukocytes to the site of inflammation.
Soluble ICAM-1 has been reported in serum, cerebrospinal fluid, urine, and bronchoalveolar lavage fluid. Elevated levels of sICAM-1 in these fluids are associated with cardiovascular disease, type 2 diabetes, organ transplant dysfunction, oxidant stress, abdominal fat mass, hypertension, liver disease, and certain malignancies. sICAM-1 promotes angiogenesis and serves as an indicator of vascular endothelial cell activation or damage. It also functions as an inhibitor of transmembrane ICAM-1 mediated activities such as monocyte adhesion to activated endothelial cells and sensitivity of tumor cells to NK cell-mediated lysis.
Principle of Test Method:
The human soluble ICAM-1 assay is a solid phase enzyme linked immunoassay designed to measure sICAM-1 in cell culture supernates, serum and plasma.