After activation eosinophil granulocytes are segregating the cationic glycoprotein EDN (eosinophil derived neurotoxin). This 18-21 kDa single stranded glycosylated protein is also known as EPX (eosinophil protein X). Together with ECP (eosinophil cationic protein) EDN belongs to the ribonuclease superfamily (Lit. 1-3). However EDN has a 100-fold increased ribonuclease activity. It is neurotoxic but not cytotoxic (Lit 4, 5). The activation of eosinophil granulocytes is important during inflammatory processes in allergic reactions. Thus EDN is a marker for eosinophil activation and degranulation.
The measurement of EDN in stool allows the detection of chronic inflammation in the gut. In the context of researching colitis ulcerosa and/or morbus crohn, measurement of EDN gives information on the activity of the disease and the prediction of a relapse.
The ImmuChrom EDN ELISA Kit is intended for the quantitative determination of EDN (eosinophil derived neurotoxin) in stool. This immunoassay enables easy, rapid and precise quantitative determination of EDN in biological samples. For research use only.
Sandwich ELISA, HRP-labelled antibody
eosinophil derived neurotoxin, eosinophil protein X, EPX, non-secretory ribonuclease, RNase UpI-2, Ribonuclease 2, RNase 2, Ribonuclease US, RNASE2
Principle of Method
The EDN-ELISA test determines human EDN according to the “sandwich”-principle. EDN in sample, standard and controls binds to polyclonal antibodies, which are coated to the microtiter plate. After a washing step a peroxidase labeled polyclonal antibody is added. A second washing step is followed by the addition of the substrate which is converted to a colored product by the peroxidase. The reaction is terminated by the addition of an acidic stop solution. The optical densities are read at 450 nm in a microtiter plate reader. The EDN concentration can be calculated from the standard curve.
In a stool sample extraction vial mix 15 mg stool with 1.5 ml extraction buffer (EXT), then vortex it until the mixture is homogenous. Transfer the resulting slurry to a plastic vial and centrifuge it for 10 min at 3000 x g. 100 μl of the supernatant are used in the test per well.
Calibration Range: 0.55 ng/ml - 35 ng/ml
Limit of Detection
Intra-assay (Within-Run) C.V.
- 8.7% (1672 ng/ml) [n = 10]
- 6.6% (730 ng/ml) [n = 10]
- 5.2% (197 ng/ml) [n = 10]
Inter-assay (Run-to-Run) C.V.
- 10.1% (1178 ng/ml) [n = 10]
- 7.8% (446 ng/ml) [n = 10]
- 8.2% (218 ng/ml) [n = 10]
1. Durack D.T., et al., Proc. Natl. Acad. Sci. USA 78, 5165 (1981).
2. Peterson C.G., et al., Immunology 50, 19 (1983).
3. Slifman N.R., et al., J. Immunol.143, 2317 (1989).
4. Gullberg U., et al., Biochem. Biophis. Res. Commun. 139, 1239 (1986).
5. Slifman N.R., et al., J. Immunol. 137, 2913 (1986).
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