Summary
Cells pass through a laser one at a time and are counted and characterised by fluorescent markers.
In depth
Cells in fluid are hydrodynamically focused; forward scatter indicates size, side scatter granularity; fluorophores identify markers. FACS can sort cells. Used in immunology, haematology and stem cell research.
Gating strategies isolate populations. Compensation corrects spectral overlap. It measures thousands of cells per second.
Remember: it measures single cells but does not give images.
In flow cytometry, cells in suspension are labelled with fluorescent antibodies or dyes and pass single file through a laser beam. Detectors record forward scatter (size), side scatter (granularity) and fluorescence at several wavelengths for each cell, at thousands of cells per second.
Data appear as histograms and dot plots, where gates select populations. Applications include counting CD4 T cells in HIV, diagnosing leukaemias, analysing cell cycle by DNA content, measuring apoptosis and sorting live cells (FACS) into pure fractions for further culture. Panels of 20 or more colours are now possible.
Example: separating B cells from T cells based on CD19 and CD3.
Frequently asked questions
What is Flow Cytometry?
Cells pass through a laser one at a time and are counted and characterised by fluorescent markers.
Which area of biology covers Flow Cytometry, and how advanced is it?
Flow Cytometry is one of the 51 topics in Lab Methods & Biostatistics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Immunofluorescence, Bioimage Analysis, Confocal Microscopy.
Why does Flow Cytometry matter?
It gives quantitative data on individual cells within large populations.
Can you give an example of Flow Cytometry?
Counting CD4 T cells in HIV patients.
What should I learn before Flow Cytometry?
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to Flow Cytometry. Intermediate topics assume the Beginner vocabulary.
What topics are related to Flow Cytometry?
The closest topics to Flow Cytometry are Immunofluorescence, Bioimage Analysis, Confocal Microscopy, Super-Resolution Microscopy. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Flow Cytometry?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Flow Cytometry. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is Flow Cytometry different from Immunofluorescence?
Flow Cytometry: Cells pass through a laser one at a time and are counted and characterised by fluorescent markers. Immunofluorescence: Fluorescent-labelled antibodies reveal the location of proteins in cells and tissues. Read both side by side and note what each one explains.
How should I study Flow Cytometry step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Immunofluorescence and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.