MICROVUETMC1-Inhibitor Plus EIA

C1-lnhibitor (C1-INH) is a multispecific, protease inhibitor that is present in normal human plasma and serum and that regulates enzymes of the complement, coagulation, fibrinolytic, and kinin-forming systems. The enzymes (proteases) regulated by this protein include the C1r and C1s subunits of the activated first component of complement, activated Hageman factor (factor XIIa), Hageman factor fragments, activated plasma thromboplastin antecedent (PTA or factor XIa), kallikrein (Fletcher factor) and plasmin.2 A deficiency of functionally active C1-INH may lead to life-threatening angioedema. Two major forms of C1-INH deficiency have been reported: the congenital form, termed hereditary angioedema (HAE) and the acquired form, which is associated with a variety of diseases, including lymphoid malignancies. Hereditary angioedema is characterized by transient but recurrent attacks of nonpruritic swelling of various tissues throughout the body. The symptomatology depends upon the organs involved. Intestinal attacks lead to a diversity of symptoms including pain, cramps, vomiting, and diarrhea. The most frequent cause of death in this disease is airway obstruction secondary to laryngeal edema occurring during an attack. There are two types of hereditary angioedema that can be distinguished biochemically. Patients with the more common type (85% of HAE patients) have low levels of functional C1-INH and C1-INH antigen. Patients with the second form (15% of HAE patients) have low levels of functional C1-INH but normal or increased levels of C1-INH antigen, which is associated with a dysfunctional protein. The variable nature of the symptoms at different time-periods during the course of the disease precludes definitive diagnosis based solely on clinical observation. Hereditary or acquired angioedema can only be definitively diagnosed by laboratory tests demonstrating a marked reduction in functional C1-INH levels in a patient’s plasma or serum. Several methods have been reported to measure C1-INH functional or antigenic levels. These methods include enzyme inhibition assays, radial immunodiffusion, immunoelectrophoresis, and inhibition of immune hemolysis. Each of these methods has disadvantages. The enzyme inhibition assay are difficult to set up and conduct on a routine basis, the immunochemical methods which measure total antigen cannot distinguish between functional and nonfunctional C1-INH protein, and the anti-C1r immunodiffusion method, which was developed to measure functional C1-INH activity, is not quantitative. The MicroVue assay is able to measure quantitatively the level of functionally active C1-INH protein present in a patient’s plasma or serum by utilizing a convenient, standardized and reproducible EIA procedure.