MSD offers a range of individual assays utilizing U-PLEX Antibody Sets that provide a rapid and convenient method for measuring biomarkers in complex matrices. The individual assays are offered on MSD GOLD Small Spot Streptavidin Plates and use the same antibody sets and diluents as the U-PLEX multiplex assays. This allows for efficient transfer between the individual assay and a higher throughput multiplex configuration. Typical of assays developed on the MSD platform, the individual assays have high sensitivity, excellent precision, provide up to five-logs of linear dynamic range, and require minimal sample volume. Interleukin-13 (IL-13) is a glycosylated immunoregulatory cytokine with two internal disulfide bonds. IL-13 is secreted by a variety of immune cells. IL-13 is involved in a number of biological processes, such as positive regulation of B-cell proliferation, macrophage activation, immunoglobulin production, protein secretion, and phosphorylation of Stat6 protein. IL-13 initially interacts with IL-13 Rα1 to form a low affinity complex. The formation of this complex triggers association with IL-4 Rα to form a high affinity complex which also functions as the type 2 IL-4 receptor complex. IL-13 also binds with high affinity to IL-13 Rα2 which is expressed as soluble intracellular protein and also on the cell surface. IL-13 is involved in number of disorders including allergic rhinitis, inflammatory bowel disease, and colorectal cancer. The U-PLEX Human IL-13 Assay provides the components for the quantitative determination of both natural and recombinant IL-13 in serum, plasma, and cell culture supernatants. The U-PLEX Mouse IL-13 Assay provides the components for the quantitative determination of both natural and recombinant IL-13 in serum, plasma, and cell culture supernatants.