Introduction Factor XIII is a proenzyme for a plasma transglutaminase previously known as fibrin stabilizing factor. Intracellular FXIII exists as a dimer of two FXIIIA molecules, whereas the circulating plasma FXIII is composed of two FXIIIA and two FXIIIB subunits (1). This tetramer is activated in the presence of thrombin and Ca2+ by separation of the two subunits and cleavage of the 37 amino acid activation peptide from the N-terminal of the FXIIIA molecule (2). Inherited factor XIII deficiency can result from mutations in either the A- or B- subunit genes (3). Factor XIIIA subunit deficiency is an autosomal recessive disorder that is characterized by a life-long bleeding tendency and complications in wound healing (4).
Principle of the Assay The AssayMax Human Factor XIII (FXIII) ELISA kit is designed for detection of human factor XIII in plasma, serum, milk, urine, saliva, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures FXIII in less than 4 hours. A murine antibody specific for FXIII has been pre-coated onto a 96-well microplate with removable strips. FXIII in standards and samples is sandwiched by the immobilized antibody and the biotinylated polyclonal antibody specific for FXIII, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.