PCT LIA > Measuring Principle
The PCT measurements are made using a "sandwich" type luminescence immunoassay and a coated-tube technique. The BRAHMS PCT LIA assay uses two monoclonal antibodies that are directed against the C-terminal and mid-regional catacalcin sequences. The anti-catacalcin antibody is immobilized on the surface of the coated tube, and the anti-calcitonin antibody is labeled using a luminescent acridine derivative.
The assay remains unaffected by calcitonin and catacalcin levels, even at high concentrations. 20-µl serum or plasma samples are used for the PCT test. The samples are incubated at room temperature for 1 hour. The samples are placed in a luminometer and hydrogen peroxide and sodium hydroxide solutions are automatically injected. These substances react with the acridine derivative bound to the anti-calcitonin antibody, which emits light as it transforms into acridone. The emitted light intensity is directly proportional to the PCT concentration.