Stemcell, 200-0998, Human Granzyme B ELISpot Kit

Human Granzyme B ELISpot Kit is designed for the quantitative detection and enumeration of cells secreting human granzyme B in a suspension of peripheral blood mononuclear cells (PBMCs). ELISpot is commonly used for evaluating specific immune responses, such as determining the frequency of activated T cell subsets in response to antigenic stimulation. Granzyme B is a serine protease secreted by activated CD8+ cytotoxic T cells as well as natural killer cells, which mediates immune responses against virus- infected and tumor cells. ELISpot is highly sensitive and can detect secreted analytes at a single-cell level. This assay is used in research of infectious diseases, cancers, allergies, and autoimmune diseases.

The assay is based on a modified version of the sandwich ELISA method, in which cells are added to ELISpot plates pre-coated with capture antibodies specific for the cytokine. The cytokine is then captured throughout the culture period and is detected by the addition of a biotinylated detection antibody, followed by streptavidin-alkaline phosphatase (SA-ALP), which binds to the biotinylated antibody. Addition of the chromogenic enzyme substrate 5-bromo-4-chloro-3-indolyl-1-phosphate (BCIP)/nitroblue tetrazolium (NBT), results in the formation of colored spots. The number, size, and intensity of these spots are directly proportional to the frequency of cytokine-secreting cells in the sample and the amount of analyte secreted.