Cell Collection
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).