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. Author manuscript; available in PMC: 2012 Aug 1.
Published in final edited form as: Nat Rev Immunol. 2012 Feb 17;12(3):191–200. doi: 10.1038/nri3158

Figure 1. A typical flow cytometry experiment.

Figure 1

Sample preparation from blood often involves Ficoll gradient separation of mononuclear cells, and sometimes cryopreservation, before staining with fluorescent antibody conjugates. Each of these steps can introduce variability in the assay results. Instrument setup involves setting voltage gains for the photomultiplier tubes (PMTs) so as to achieve optimal sensitivity. To the extent that this is not standardized, it becomes a source of variability as well. Data acquisition involves passing the stained cells through a laser beam and recording the fluorescence emission from all of the bound antibody conjugates. Here, the main variable is the type of instrument, including the lasers and optical filters used. This is followed by data analysis, in which cell populations of interest are defined and reported on, which is another significant source of variation. Ref., reference; SD, standard deviation.