ßIG-H3 ELISA is designed to measure ßIG-H3 (beta-induced H3) in urine, serum or cell culture supernatant of human origin. ßig-h3 is a 68 kD protein induced in diverse cell types by the growth factor Transforming Growth Factor-ß (TGF-ß) that is secreted into the extracellular matrix and is involved in cell growth, differentiation, adhesion, and wound healing. ßig-h3 expression is altered in various conditions including tumorigenesis, breast cancer, corneal dystrophy, osteogenesis, and atherothrombosis. ßig-h3 is elevated in the urine of patients with cyclosporine nephrotoxicity and with type 2 diabetes in whom it shows positive correlation with the albumin excretion rate, making it a useful biomarker of renal dysfunction due to diabetes in its earliest phases and in monitoring clinical progression of diabetic nephropathy.
To complete the assay, standard or sample containing ßig-h3 in the soluble phase is added to microtiter wells coated anti-human ßig-h3 antibody. The ßig-h3 in standard or sample is captured by this antibody on the solid phase, and unbound materials are washed away. Biotinylated anti-human ßig-h3 antibody is then added, followed by a reaction with Streptavidin –HRP conjugate to label the biotinylated probe with enzyme. After washing, ßig-h3 bound to the capture antibody on the stationary phase is detected after addition of a chromogenic substrate. Samples with absorbance values above the standard curve should be diluted before assay.