Description
Principle of the assay: The 13-defensin 2 in standards and samples is bound to an available excess of polyclonal antibodies against 13-defensin 2, which are immobilized on the surface of the microtiter plate. After a washing step, to remove all interfering substances, the determination of bound 13-defensin 2 is carried out by adding a polyclonal anti 13- defensin 2 antibody, which is horseradish peroxidase labeled. After a washing step to remove the unbound components, the peroxidase substrate tetramethylbenzidine is added. Finally, the enzymatic reaction is terminated by an acidic stop solution. The color changes from blue to yellow and the absorbance is measured in the photometer at 450 nm. The intensity of the yellow color proportional to the 13- defensin 2 concentration in the sample. A dose response curve of absorbance unit (optical density, OD at 450 nm) vs. concentration is generated using the values obtained from the standards.
Background: The beta-defensins are an integral part of the congenital immune system and contribute with their antimicrobial effect to the barrier function of intestinal epithelial cells. Defensins exert a variable degree of antimicrobial activity against bacteria, fungi, and some enveloped viruses. Vertebrate defensins are classified as alpha- or betadefensins, based on their pattern of disulfide bridges. Nine human defensins of epithelial origin have been found, three of them being beta-defensins (HBD-1, -2 and -3). The expression of beta-defensins is induced by the pro-inflammatory cytokines and also through microorganisms (e.g. F. coli, H. pylori or P. aeruginosa). A beta-defensin-2 deficiency can, for example, be observed in the intestinal mucous of subjects with Crohn's disease. The defense system of the mucous membrane is therefore restricted and allows an increased invasion of bacteria, which could possibly lead to a typical infection in Crohn's disease subjects. Whether the beta-defensin-2 deficiency could even play a role in the development of Crohn's disease is currently being researched. As is the possibility that it is the probiotic bacterium, which produces beta-defensin