Beta-Defensin 2 ELISA

The β-defensin 2 in standards and samples are bound to an available excess of polyclonal antibodies against β-defensin 2, which are immobilized on the surface of the microtiter plate. After a washing step to remove all interfering substances, the quantification of bound β-defensin 2 is carried out by adding a polyclonal anti-β-defensin 2 antibody, which is labeled with horseradish peroxidase. 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 is proportional to the β-defensin 2 concentration in the sample. A dose response curve of absorbance unit (optical density, OD at 450 nm) versus concentration is generated using the values obtained from the standards. The concentration of β-defensin 2 present in the samples is determined directly from this curve.