Cellular Luminescence (Reactive Oxygen Species)
Cellular chemiluminescence (CL) is the production of light occuring upon chemical reaction of activated cells like neutrophil granulocytes, monocytes or macrophages when phagocytosis as the first immune response is activated in order to protect the organism from invaders. After ingestion of the external object, reactive oxygen species such as H2O2, OH- and O2- are produced resulting in luminescence of a very small intensity. To enhance the chemiluminescent effect, substrates like Luminol and Lucigenin can be added.
The phagocyte cellular chemiluminescence response provides insight into some specific diseases like bacterial and viral infections, Diabetes mellitus, Arthritis, Cancer, etc. Cellular chemiluminescence is also a very sensitive assay for determing the toxicity of environmental or occupational agents on phagocytic cells. Insufficiency and hyperactivity of oxygen-dependent phagocytosis of granulocytes can easily be detected by using cellular chemiluminescence.
To enhance the chemiluminescent effect, substrates that are known to react chemiluminescently with reactive oxygen metabolites can be addded and the following light-emission can be detected. Luminol and Lucigenin are very commomly used substances in these kind of assays:
- Luminol reacts with H2O2 and as a result the electronically activated product emits photons at a wavelength of 425 nm.
- Lucigenin reacts with O2- that causes an emission of light at 470 nm.
This emitted light can be monitored by luminometers with temperature control. The light quantity can be increased by adding an effective catalysator, such as the enzyme Myeloperoxidase (MPO), that is found in granulocytes and that produces native light emission. MPO reacts with H2O2, O2 and Cl to HOCl (hypochlorous acid) that destroys invaded foreign bodies.