The number of cells you need to collect during analysis to have statistically significant results can vastly differ depending on the sample and frequency of your cells. If you have a sample with an abundant cell type such as T cells in human peripheral blood, which represent around 20% to total mononuclear cells, you will have to collect and stain less cells than if you are looking at NK cells which have a frequency around 5%. The table below shows an example of how the frequency of cells can affect the number of cells collected.
Table 5: Cell Frequency
Starting Population |
Frequency |
Number Collected |
---|---|---|
1,000,000 |
10% |
100,000 |
1,000,000 |
1% |
10,000 |
1,000,000 |
0.1% |
1,000 |
In addition to the number of cells, the number of markers simultaneously detected to look at cell subsets can affect the number of cells that are needed to be acquired; generally an increase in markers requires more cells. Finally performing the right controls, to determine the variation and allow definition a positive or negative is also very important. More detailed information on collecting enough events can be found in an article by M Roederer in Cytometry Part A. (Roederer M (2008). How many events is enough? Are you positive? Cytometry, 73A:384-385).