Complement C1 inhibitor (inactivator) immunological test system.

§ 866.5250 Complement C 1 inhibitor (inactivator) immunological test system. (a) Identification. A complement C 1 inhibitor (inactivator) immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the complement C 1 inhibitor (a plasma protein) in serum. Complement C 1 inhibitor occurs normally in plasma and blocks the action of the C 1 component of complement (a group of serum proteins which destroy infectious agents). Measurement of complement C 1 inhibitor aids in the diagnosis of hereditary angioneurotic edema (increased blood vessel permeability causing swelling of tissues) and a rare form of angioedema associated with lymphoma (lymph node cancer). (b) Classification. Class II (performance standards).