Flow cytometry gating

 Flow cytometry is a technique for detecting and quantifying the physical and chemical properties of a population of cells or particles. 

A sample comprising cells or particles is suspended in a fluid and injected into a flow cytometer device in this procedure.I

n flow cytometry, the term "gating" refers to the process of choosing a certain cell type.

Gating is a term used frequently in flow cytometry to describe the process of picking a specific section of data to study. On histograms, linear gates are employed, however on dot plots, polygons, rectangles, or circles can be used to gate.Polygon gates (freeform gates), histogram gates, quadrants, and boxes are the four primary types of gates. Each of them can be used to select certain cell populations. We can pick CD62L+ (right gate) and CD62L populations using the histogram gates in Fig. 1d, for example (left gate).These gating mechanisms can then be used to identify cell populations that can be further investigated. Quadrant gates are also commonly employed to divide protein expression into four areas: Q1, Q2, Q3, and Q4.Quadrants are used to gate CD4 and CD8 expression in mouse thymii (Fig. 1b–c).Box gates, like histogram gates, can be used to select a specific cell type; in this case, CD8+ T cells are selected (Fig. 1a, bottom panel). Gating is likewise hierarchical, with each gate building on the one before it.A typical gating hierarchy that would be employed in mouse thymii stained with CD4 and CD8 is shown below (Fig. 1b, c). The live gate, P1, is an upstream gate, whereas the quadrant gates Q1-Q4 are downstream gates, meaning they are after P1. As a result, quadrant gates 1–4 are considered to be P1's dependents.

Typical gating hierarchy.

P1 (live gate)

–– Q1 (CD8+CD4−)

–– Q2 (CD8+CD4+)

–– Q3 (CD8−CD4+)

–– Q4 (CD8−CD4−)

Fig. 1 Interpreting dot plots. Histograms, dot plots, and density plots are shown on various

lymphocyte populations in human and mouse. Cells were harvested, stained with the antibodies indicated below, acquired on a BD LSRFortessa™ and analyzed using FlowJo® software. (a) hCD8 A405 expression is shown in human PBMCs using both a histogram (top panel) and dot plot using SSC-A (bottom panel). (b, c) Mouse thymocytes were stained for mCD4 and mCD8 and are shown using a pseudocolor dot plot (top panel, b), monochromatic dot plot (bottom panel, b), and density plot (c). (d) Human PBMCs were stained for hCD62L, and gates were set on the negative and positive populations