Method Description

The Quidel C1 inhibitor enzyme immunoassay for the quantitation of functional C1 inhibitor protein in human serum or plasma is a four-step procedure. In the first step, standards, controls, and test specimens are incubated with C1 esterase inhibitor (C1-INH) reactant (biotinylated, activated C1s). During this incubation, functionally active C1-INH present in the standards, controls, and test samples will bind to the biotinylated C1-INH reactant to form complexes. In the second step, an aliquot of the incubation mixtures containing biotinylated C1-INH reactant is added to microtiter wells pre-coated with avidin. C1-INH reactant: C1-INH complexes present in the standards, controls, or specimens will bind to the avidin-coated microassay wells. After incubation, a wash cycle removes unbound material. In the third step, horseradish peroxidase (HRP)-conjugated goat anti-C1-INH is added to each test well. During this step, the HRP-conjugated anti-C1-INH binds to the C1-INH reactant: C1-INH complexes, which were captured on the surface of the avidin-coated microassay wells. After incubation, a wash cycle removes excess conjugate. In the fourth step, a chromogenic enzyme substrate is added to each microassay well. The bound HRP-conjugate reacts with the substrate forming a blue color. After incubation, the enzyme reaction is stopped chemically, forming a yellow color and the color intensity is measured spectrophotometrically at 450 nm. The color intensity of the reaction mixture is proportional to the concentration of functional C1-INH protein present in the test specimens, standards, and controls.(Package insert: C1-Inhibitor Enzyme Immunoassay. Quidel; 09/2021)