Automated immunoassay analyzers from several different manufacturers are in commercial use and still others are in development. The technical demands of these assay markets requires detection technologies which are highly sensitive, not overly prone to interferences, robust and simple to use. Chemiluminescent processes possess the necessary sensitivity characteristics and thus are well suited for these demanding applications. Luminescent processes can be categorized broadly as chemiluminescent reactions involving purely chemical reactions using compounds prepared in the laboratory and usually involving a highly oxidized species, bioluminescent reactions arising from compounds originating in a living organism, and electrochemiluminescent reactions involving the use of electrical current to produce a light-emitting species. Assays can utilize an enzyme or chemical catalyst as a label or can use the chemiluminescent compound directly as a label.
Most assays are heterogeneous and require separation of bound from unbound label.
Homogeneous assays which require that the light-producing reaction be modulated by binding of the ligand to its receptor are more difficult to develop but offer advantages in assay simplification. New evidence has emphasized an inflammatory and, perhaps, infectious contribution to the atherosclerotic process. CRP may be useful in detecting this process and providing important prognostic information about patients with asymptomatic heart disease, unstable angina, and myocardial infarction. Whether CRP is simply a marker or actually contributes to the atherosclerotic process is yet to be determined. CRP represents a challenge to the laboratory in that newer, more sensitive assays will have to be developed to fully explore the use of this important analyte.