Neutrophil elastase, a major serine proteinase in man, is predominantly present in the azurophilic granules of neutrophils. Elastase has a broad range of extracellular matrix substrates including elastin, proteoglycans, collagen and fibronectin. The action of elastase is controlled by serine proteinase inhibitors. Elastase, when released during inflammation, is rapidly bound by its two main inhibitors, alpha1-PI and alpha2-macroglobuline to form elastase-inhibitor complexes. In addition, mucosa secretions may contain the locally secreted elastase inhibitors elafin/SKALP and SLPI. When secreted at sites of inflammation elastase can cause severe tissue damage. An important role has been suggested for elastase in various inflammatory disorders, including pulmonary emphysema, sepsis, arthritis, nephritis and certain skin diseases. Elastase induces the production of IL-8 in human bronchial epithelial, a proces that occurs in part through TLR4. In plasma of healthy individuals approx. 55 ng/ml (29 – 86 ng/ml) elastase is present.
The human Elastase ELISA kit is to be used for the in vitro quantitative determination of human Elastase in plasma and cell culture supernatant samples.
The human neutrophil Elastase ELISA is a ready-to-use solid-phase enzyme-linked immunosorbent assay based on the sandwich principle with a working time of 3½ hours.
The efficient format of a plate with twelve disposable 8-well strips allows free choice of batch size for the assay.
Samples and standards are captured by a solid bound specific antibody.
Biotinylated tracer antibody will bind to captured human neutrophil elastase.
Streptavidin-peroxidase conjugate will bind to the biotinylated tracer antibody.
Streptavidin-peroxidase conjugate will react with the substrate, tetramethylbenzidine (TMB).
The enzyme reaction is stopped by the addition of oxalic acid.
The absorbance at 450 nm is measured with a spectrophotometer. A standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentrations of the human neutrophil elastase standards (log).
The human neutrophil elastase concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.
The linearity of the assay was determined by serially diluting a sample containing 18 ng/ml human neutrophil elastase. The diluted samples were measured in the assay. The line obtained a slope of 1.35 and a correlation coefficient of 0.999.