Flow Cytometry
Flow cytometry is a laser-based technology that simultaneously measures multiple physical and chemical characteristics of single cells or particles as they flow in a liquid stream through one or more laser beams. Detectors measure scattered light and fluorescence signals from cells labelled with fluorescent dyes or antibodies, allowing rapid, multi-parameter analysis of thousands of cells per second. It is widely used in immunophenotyping, cell cycle analysis, apoptosis detection, and clinical diagnostics such as CD4 counting in HIV management.
Key Parameters Measured by Flow Cytometry
| Parameter | Signal Type | Detector | Biological Information | Example Application |
|---|---|---|---|---|
| Forward Scatter (FSC) | Light scatter (low angle) | Photodiode | Cell size / volume | Distinguishing lymphocytes from monocytes |
| Side Scatter (SSC) | Light scatter (90°) | PMT | Cell granularity / complexity | Identifying granulocytes |
| Fluorescence (FL1) | Emission ~530 nm | PMT | FITC-labelled antibody binding | CD4+ T-cell counting |
| Fluorescence (FL2) | Emission ~585 nm | PMT | PE-labelled antibody binding | CD8+ T-cell counting |
| Fluorescence (FL3) | Emission >650 nm | PMT | DNA content (PI staining) | Cell cycle phase analysis |
Interactive Tools
FlowJo Software (Trial)
Industry-standard software for analysing and visualising flow cytometry data
Open ToolBD Biosciences Spectrum Viewer
Interactive tool for designing multi-colour flow cytometry panels
Open ToolKhan Academy — Cell Biology
Background on cell cycle phases relevant to flow cytometry analysis
Open Tool
Wikimedia Commons, CC BY-SA
Related Terms
Cell Cycle
The cell cycle is the ordered sequence of events by which a cell grows, replicates its DNA, and divides into two daughter cells. It consists of interphase (G1, S, and G2 phases) and the mitotic phase (mitosis and cytokinesis). Precise regulation of the cell cycle through checkpoints is essential for normal development; dysregulation leads to cancer and other diseases.
Proteomics
Proteomics is the large-scale study of the entire complement of proteins (the proteome) expressed by a genome, cell, tissue, or organism at a given time and under specific conditions. Unlike the static genome, the proteome is highly dynamic — proteins vary in abundance, post-translational modifications (PTMs), localisation, and interactions in response to cellular state and environment. Mass spectrometry combined with two-dimensional gel electrophoresis or liquid chromatography is the primary technology platform used to identify, quantify, and characterise proteins at a systems level.
From Greek "kytos" (vessel, cell) + "metron" (measure) + Latin "fluere" (to flow). The technology was pioneered by Mack Fulwyler in 1965 (cell sorter) and Wolfgang Göhde in 1968 (fluorescence-based analysis).