Samples and a POD-labeled VN antibody are simultaneously incubated in the antibody-precoated microtiter plate wells. During the incubation, anti-VN which is precoated on the wells binds sample VN, and the sample VN is in turn tagged by POD- anti-VN. The reaction between POD and the substrate (H2O2, TMBZ) results in a color development. The amount of sample VN is determined by measuring absorbance using an EIA plate reader. Accurate VN sample concentrations can be determined by comparing their specific absorbances with the absorbance obtained for the Standard plotted on a standard curve.
Vitronectin is a major cell adhesion protein found in plasma (at high concentrations of 200–300 mg/L), platelets, the extracellular matrix of tissues and atherosclerotic plaques. VN interacts with many different macromolecules, including cell surface integrin receptors, inactive anti-thrombin/thrombin complex, collagen and other extracellular matrix components, plasminogen activator inhibitor type 1, and heparin. Through these interactions, VN contributes in various ways to the regulation of the immune and hemostatic systems. Clinically, it has been noted that a significant decrease of plasma vitronectin levels is observed for liver disorders with high fibroblastic activity, such as liver cirrhosis.
