Principle of Assay
Human IL-4 ELISpot Kit (A341807) is a sandwich ELISA designed for the sensitive and quantitative measurement of human IL-4 in peripheral blood mononuclear cells (pbmcs). The assay utilizes a 96-well microtiter plate pre-coated with an antibody specific for IL-4. Standards and samples are added to the wells, allowing IL-4 present in the samples to bind to the immobilized capture antibody. After washing, a biotinylated detection antibody specific for IL-4 is added, forming an antibody–antigen–antibody complex. Unbound detection antibody is removed by washing, followed by the addition of streptavidin conjugated to horseradish peroxidase (HRP). Following incubation and washing, TMB substrate is added, resulting in a colorimetric reaction that produces a blue color which turns yellow upon addition of stop solution. The intensity of the color is directly proportional to the concentration of IL-4 in the sample. The concentration of IL-4 is determined by measuring the absorbance at 450 nm and comparing the results to the standard curve.