Flow cytometry is a laboratory technique used to count and analyze biological cells. The instrumentation typically includes a flow chamber, as well as a laser and light detector. Filters and color detectors usually derive data that are processed by a computer, which organizes the information into a graph called a histogram. The applications of flow cytometry range from detecting types of cells in a sample, to analyzing deoxyribonucleic acid (DNA) content, enzyme activity, or proteins. It is also used to monitor cancer and stem cells, measure blood before and after an organ transplant, and characterize blood of people with immunodeficiency diseases.
Living and dead cellular material can be distinguished by using fluorescent dyes. This principle used in the applications of flow cytometry can be applied to tracking DNA throughout the cell cycle. It can also be determined how much of a sample may be in a dividing phase. When certain compounds are added to a sample, they can emit specific colors of light when exposed to a laser beam. Metabolic states of cells are often analyzed this way; some substances are often used to detect damaged populations as well.
A flow cytometer typically includes a flow chamber, which allows quick passage of one cell at a time. The samples are hit by a laser and the light passes on to a detector; light reflected at small angles, called forward scatter, provides information on each cell’s size. Side scatter light moves in other directions and a detector often uses this to analyze the interior of the cell. Both measurements are often useful for monitoring immune system cells. Filters distribute light to color detectors, which can detect yellow and green, or other colors in some cases, and send these data off for computer analysis.
Detecting blood cells, as well as those in bone marrow or lymph, is one of the applications of flow cytometry. Whether death is caused by environmental factors or a programmed sequence called apoptosis can also be determined. Flow cytometry is often used to detect and characterize blood cancers such as leukemia. Specific types of disease and the stage can usually be determined, and residual cancer cells detected after treatment as well.
The health of bone marrow can be assessed. Also, applications of flow cytometry include the determination of donor and host compatibility for an organ transplant. It is often used to count red blood cells and platelets as part of clinical tests. Another one of the applications of flow cytometry is quality control of laboratory processes, so researchers can be assured that their results are accurate.