What daily quality control should be performed for quantitative flow cytometric assays?

This question is addressed in detail by CAP checklists FLO.23737, FLO.23800, and FLO.23925.

Depending on quantitative flow cytometric assays, different type of control(s) and their frequency of evaluation might vary.

For CD34+ stem cell measurements, regardless of whether single or dual platform methods are used, two levels of external controls are needed. One of the levels of these controls should be at or near clinical decision levels. Typically, an individual being readied for peripheral stem cell pheresis has a 5-20 CD34+ stem cells/µL concentration. The low CD34 control, therefore, should be near this concentration. Stem cell controls should be run each day of analysis.

For lymphocyte subset assays, one level of external control is sufficient for dual platform measurements, but two levels of external control are needed for single platform measurements. If two levels of control are used, the low one should be at or near clinical decision levels. For example, a HIV+ individual is considered to have a low CD4+ lymphocyte count of 200 cell/µL and the low CD4 control should be around this level. Lymphocyte subset control(s) should be run each day of analysis.

Preferably, commercial controls are used for quantitative assays. The laboratory must verify the recovery ranges for each lot supplied by the manufacturer prior to putting them to use. If commercial controls are not available, the laboratory director must implement an equivalent procedure to fulfill the level requirements.