NGAL

Neutrophil Gelatinase Associated Lipocalin (NGAL) is a member of the lipocalin family ⁽¹⁾ and is secreted from specific granules of human neutrophils upon activation of the cells. ⁽²⁾ The lipocalin family consists of more than 25 members ^(4), each member is characterised by its ability to bind small lipophilic substances in their hydrophobic core. ^{(1, 4)} Lipocalins tend to associate with other proteins and as its name suggests, NGAL has been found to associate with gelatinase ⁽¹⁾ however it mainly exists as monomeric and homodimeric forms. (1) The lipocalin family are not specific to just one ligand but can bind several different ligands. ⁽⁴⁾

 

The function of NGAL although not well known is thought to be important during the inflammatory response. ^(1-4) NGAL is present at low levels in healthy individuals however elevated levels of NGAL have been found to both accurately and specifically distinguish between acute bacterial and viral infections. ⁽³⁾ Elevated levels have also been associated with acute peritonitis, cystic fibrosis, and a number of other conditions. ⁽³⁾

 

Perhaps the most important is the possibility of using NGAL as a biomarker to detect Acute Kidney Injury also referred to as acute renal failure.

Acute kidney injury (AKI) is a common complication particularly after cardiopulmonary bypass. The condition can be life threatening if not detected early, unfortunately because there are few specific and reliable markers available for acute kidney injury there are often delays in diagnosing and treating affected individuals. ⁽⁵⁾

At present diagnosis is based on the measurement of creatinine in the serum however this method can be unreliable as levels may not change after injury until 50% of kidney function has already been lost. ^(6). Furthermore creatinine levels have been known to fluctuate with a number of factors including gender, age, and weight. Recent studies have shown that NGAL levels in the serum and urine are greatly increased just a short time after suffering acute kidney injury making NGAL an ideal early marker for AKI.

NGAL levels are also raised in the acute stages after stroke, the levels then remain elevated for some time after. ^{(7, 8)} In developed countries stroke is the third leading cause of death and the leading cause of adult disability. Determination of the type of stroke is therefore very important and crucial in deciding on the correct treatment. Cerebrovascular disease is complex and currently a number of different procedures are used in its diagnosis many of which are both costly and time-consuming. Current diagnostic procedures include computed axial tomography (CT scan) and magnetic resonance imaging (MRI scan) to view the brain, skull or spinal cord. Other scans can also be used to view the blood vessels that supply the brain. Biochemical markers such as NGAL specific for each of the different types of stroke are therefore useful in determining the pathological processes that precede the onset of stroke as well as the development of tests to predict the outcome and risk of further stroke episodes.

 

Products available from Randox

 

Human Recombinant Protein

 

 

 

Antibody

 

 

 

 

 

References

 

1. Kjeldsen L., Bainton D.F., Sengelov H. and Borregaard N. (1994) Identification of Neutrophil Gelatinase- Associated Lipocalin as a Novel Matrix Protein of Specific Granules in Human Neutrophils. Blood. 83(3): 799-807.

 

2. Falke P., Elneihoum A.M. and Ohlsson K. (2000) Leukocyte Activation: Relation to Cardiovascular Mortality after Cerebrovascular Ischemia. Cerebrovasc. Dis. 10(2): 97-101.

 

3. Xu S. and Venge P. (2000) Lipocalins as biochemical markers of disease. Biochim. Biophys. Acta. 1482(1- 2): 298-307.

 

4. Kjeldsen L., Koch C., Arnljots K. and Borregaard N. (1996) Characterization of two ELISAs for NGAL, a newly described lipocalin in human neutrophils. Immunol. Methods. 198(2): 155-164.

 

5. Dent C., Ma Q., Dastrala S., Bennett M., Mitsnefes M. (2007) Plasma neutrophil gelatinase-associated lipocalin predicts acute kidney injury, morbidity and mortality after paediatric cardiac surgery: a prospective uncontrolled cohort study. Critical Care 11:R127

6. Nguyen M., Devarajan P (2008) Biomarkers for the early detection of acute kidney injury. Pediatr Nephrol 23:2151–2157