Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL), 24p3, siderocalin, or neutrophil lipocalin (NL), is a secretory glycoprotein expressed in liver, lung, kidney, adipocytes, activated neutrophils and macrophages.
Lipocalin-2 is upregulated under various inflammation and infection conditions and can be served as a sensitive biomarker for various renal injuries. Serum levels of lipocalin-2 are positively correlated with obesity, insulin resistance, hyperglycemia, coronary heart disease and fatty liver disease in humans.

This assay is a sandwich ELISA using antigen-affinity-purified polyclonal antibodies against mouse LCN2. The immunoplate is pre-coated with anti-mouse LCN2 capture antibody. Standards and samples are added to the wells and any mouse LCN2 present is captured by the immobilized antibody. After wash step to remove any unbound substances, a biotin labelled anti-mouse LCN2 detection antibody is added. After washing procedure, streptavidin-HRP conjugate (STP-HRP) is added. After the last wash step, an HRP substrate solution is added and colour develops in proportion to the amount of mouse LCN2 bound initially.  The assay is stopped and the optical density of the wells determined using a microplate reader. Since the increases in absorbance are directly proportional to the amount of captured mouse LCN2, the unknown sample concentration can be interpolated from a reference curve included in each assay.

A. Typical representation of standard curve

The following standard curve is provided for demonstration only. A standard curve should be generated for each set of sample assay.  

LCN2 (ng/mL)	Absorbance (450 nm)	Blanked Absorbance
0	0.074	0
0.156	0.122	0.048
0.312	0.162	0.088
0.625	0.239	0.165
1.25	0.406	0.332
2.5	0.707	0.633
5	1.236	1.162
10	2.082	2.008

 

B. Sensitivity

The lowest level of lipocalin-2 that can be detected by this assay is 0.156 ng/mL.

 

C. Specificity

The antibody pair used in this assay is specific to human lipocalin-2 and does not cross-react with mouse and rat lipocalin-2, and other cytokine or hormone molecules.

1. Sun WY, Bai B, Luo C, Yang K, Li D, Wu D, Félétou M, Villeneuve N, Zhou Y, Yang J, Xu A. Lipocalin-2 derived from adipose tissue mediates aldosterone-induced renal injury. JCI insight. 2018 Sep 6;3(17).
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