Fluorescence-Activated Cell Sorting (FACS) is a laboratory method technicians can use to sort cells in a sample. Using fluorescent dyes, they can tag specific proteins that may be present on some of the cells and pass them through a specialized device to pull those cells out. This can be useful for a range of activities including diagnostic medicine, research, and processing of donor materials. The equipment can be expensive and specific training is needed, so not all labs offer this technology.
In this process, the technician starts by adding one or more dyes to the sample. Each dye is designed to attach to a specific protein. The sample is suspended in a container that vibrates at very high speed to force cells out into a tube one at a time. A laser passes through the cell, with a detector on the other side to identify light scatter, which can be used to collect information about cell type and viability. Secondary detectors pick up fluorescent emissions if the laser stimulates the dye.
The device applies an electrical charge to the cell on the basis of the laser reading, and then returns to neutral to make room for the next droplet. Charged cells drop into different sorting containers. Using fluorescence-activated cell sorting, technicians can pull out two or more types of cells from a sample. Cells that do not contain the proteins of interest can be shunted to other containers, along with empty droplets and dead cells, if the machine is set to sort them out at the same time.
Technicians might use fluorescence-activated cell sorting for an activity like counting immune cells. For example, the machine could tag T and B cells in a sample to provide information about their concentrations. Numerous plots can be generated automatically with data from the fluorescence-activated cell sorting procedure. These can be utilized in research or compared with samples from healthy patients to determine if a sample is abnormal.
This is one among several technologies available for lab analysis. The best option for a sample can depend on the kind of data needed and limitations like time and cost. Fluorescence-activated cell sorting can be extremely fast, which can be a distinct advantage for processing high volume samples. Equipment expense can be a limiter in small labs with minimal resources that might not be able to make the technology pay for itself, in which case they may send samples out if they need this testing.