Quality control in flow cytometry for diagnostic pathology. I. Cell surface phenotyping and general laboratory procedures.

Flow cytometric analyses have become commonplace in the clinical laboratory for determining cell lineage and for quantitation of cells bearing a given phenotype. Because these assays are being conducted to support diagnoses or assist in determining therapy, it is crucial to ensure that these tests are highly accurate and reproducible within a laboratory and among laboratories involved in similar endeavors. This quality assurance has been slow evolving in clinical flow cytometry for a variety of reasons: the exquisite sensitivity and delicacy of the instrumentation that recognize previously undetectable variations in staining; the constant improvement of the hardware and software; the rapid development of new techniques and reagents of clinical interest; and the failure of any existing specialty or subspecialty to encompass all aspects of flow cytometry. This article provides an overview of quality assurance necessary for the flow cytometric analysis of cell surface markers. Practical experience, published studies, and suggested guidelines from accreditation agencies have been combined to develop the text.