The importance of area scaling with FACS DIVA software

With the release and use of the Becton Dickenson FACS Diva Software, the use of Area as the default parameter came into play. As such, the use of area as a calculated parameter, methods were needed to be employed to ensure doublet discrimination and proper display on standard FSC/SSC. Improper setting of forward area scaling can alter the display cell populations. This combined with improper area gating strategy can lead to doublet inclusion which in sorting rare events can compromise sort purity. In extreme cases where area scaling with the individual lasers is ignored, differences can exist between Area and Height where compensation will likely not be optimal, particularly if one parameter – usually height is saturated. In addition, area scaling can impact population grouping. As FSC and individual laser area scaling is a function of event size, the most common error is to accept the setting determined by CS&T, which are 3.2 µm particles and proceed with the sample(s) without regard to the sample’s actual size. With cellular events smaller or more likely larger than the CS&T beads, this will make the area scaling settings less than optimal. Analysis and sorting rare events with populations larger than the CS&T beads can be compromised if adjustments in FSC area scaling are not addressed. Proper FSC and laser area scaling must be determined empirically for each sample. Examples of the effects of sample size on area scaling will be presented in addition to gating and templates for determining area scaling.