|A flow cytometer|
It is a technique that uses a very sophisticated equipment that can differentiate among cells looking otherwise very similar cells and also helps undertsand how theses cells fight against microbes. It is based on the phenomenon of fluorecsence (light scattering, fluorescence emission) that vary with the size and content of the cells. In addition, it also uses molecular tools, which are antibodies (yes, the same produced by our immune system) to which a fluorescent molecule was attached. Antibodies have the ability to lock onto a target molecule and to recognize highly selectively molecular targets found on certain cells only. Pretty much like "missiles", these antibodies will be guided to the cells, will lock on them and send the light signal which allow their identification by the cytometer. This technique has revolutionized the knowledge in immunology!
Mass cytometry also uses antibodies but, in this case, antibodies are not attached to fluorescent molecules but to chemical elements present in nature, which are then detected by a mass spectrometer (a device that detects molecules by their mass). There are two advantages of this method over flow cytometry. First, many more of these elements are available as compared with fluorochromes. Second, these elements can be easily combined whereas sometimes fluorochromes having close fluorescent properties can not be easily identified separately. Therefore, when flow cytometry was limited to the simultaneous detection of several parameters (typically less than 10), the mass cytometry can analyze tens. The information on a per cell basis is much more complete!
|The result of an ELISA|