Interleukin-2 (Il-2) is produced by T-cells in response to antigenic or mitogenic stimulation. It is is required for T-cell proliferation and other activities crucial to regulation of the immune response. IL-2 can also stimulate B-cells, monocytes, lymphokine-activated killer cells, natural killer cells, and glioma cells. BioVision’s IL-2 (Human) ELISA Kit is based on the Sandwich-ELISA principle. The micro ELISA plate provided in this kit has been pre-coated with an antibody specific to Human IL-2. Standards or samples are added to the micro ELISA plate wells that bind to the specific antibody. Then a biotinylated detection antibody specific for Human IL-2 and Avidin-Horseradish Peroxidase (HRP) conjugate are added successively to each micro plate well and incubated. The wells are washed, a TMB substrate solution is added to the wells and blue color develops in proportion to the amount of IL-2 bound. The enzyme-substrate reaction is terminated by the addition of stop solution and the color turns yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450 nm. The OD value is proportional to the concentration of Human IL-2. The concentration of Human IL-2 in the samples can be calculated by comparing the OD of the samples to the standard curve.