Use of quality control standards in clinical flow cytometry

Flow cytometry is important in the clinical laboratory, especially in hematology and cancer diagnosis. With newer applications being continuously developed clinicians who will use the results and laboratory staff who produce them should be aware of the instrumental quality control procedures required. This will allow evaluation of the reliability as well as the comparison of results between different laboratories. While information about sample preparation as well as staining procedures is easily available, information about instrumental quality control procedures is less so. Various standards and controls are available commercially and their correct choice and usage requires an understanding of the methodology of instrumental quality control. Methods to evaluate the precision, sensitivity and accuracy of measurements are discussed. Most laboratories report immunophenotyping data as the percentage of antibody positive cells and make no attempt to quantitate the amount of antibody binding per cell. Methods for quantitating the number of bound antibody molecules per cell along with a simple technique to compare results between laboratories are discussed. These techniques should encourage laboratory staff and clinicians to standardise methodology and to exchange patient data between laboratories.