After activation eosinophile granulocytes are segregating the cationic glycoprotein EDN (eosinohil 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 belong to the ribonuclease superfamily. However EDN has a 100-fold increased ribonuclease activity. It is neurotoxic but not cytotoxic. The activation of eosinophile granulocytes is important during inflammatory processes in allergic reactions. Thus EDN is a marker for eosinophile activation and degranulation.
The measurement of EDN in stool allows the detection of clinical or subclinical chronic inflammation in the gut. In patients with colitis ulcerosa and/or morbus crohn, the measurement of EDN gives information on the activity of the disease and the prediction of a rezidiv.
Sample Stool, serum
Sample volume 100 mg, 100 µl
Calibration 6 point
Incubation time 1h, 1h, 15 min
Principle of the method
The EDN-ELISA test determines human EDN according to the “sandwich”-principle. EDN in sample, standard and controls binds to monoclonal antibodies, which are coated to the microtiterplate. After a washing step a peroxidase labeled polyclonal antibody is added. A second washing step is folled 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 microtiterplate reader. The EDN concentration can be calculated from the standard curve.