Final answer:
Side scatter in flow cytometry measures cell complexity or granularity by detecting fluorescence emitted from fluorophore-labeled antibodies bound to specific cell markers, allowing for differentiation and sorting of cell populations.
Step-by-step explanation:
Understanding Side Scatter in Flow Cytometry
In flow cytometry, side scatter measures the complexity or granularity within cells. As a cell passes through the laser light, the fluorescence emitted from fluorophore-labeled antibodies that bind to specific cell markers is detected by side-scatter detectors. This method is crucial for distinguishing different cell populations based on the presence or absence of certain proteins, such as CD8 in the given example.
Flow cytometry histograms display the data collected from both forward- and side-scatter detectors, with side scatter typically placed on the x-axis to represent the fluorescence of each cell. The histogram peaks indicate the number of cells expressing a certain feature; for instance, a peak with higher side scatter (fluorescence readings) corresponds to cells labeled with an antibody, indicating the expression of the particular protein.
Moreover, the fluorescence-activated cell sorter (FACS) is a form of flow cytometry capable of not just counting but also physically separating cells based on fluorescence intensity. Cells bound by fluorescence-emitting antibodies are recognized, and the sorter assigns a specific charge correlating with the wavelength of the fluorescent light.
An electrostatic deflector then sorts the cells into collecting pools based on their charge. The process yields highly purified cell subpopulations for research purposes.
Total understanding of flow cytometry is vital for applications such as monitoring immune system cells in diseases like HIV. The technology is sophisticated, utilizing fluorescence-labeling of antibodies specific to cell-membrane proteins and analyzing them as they pass individually through a narrow capillary tube, providing a count as well as a relative fluorescence measurement of the cells.