Multicenter study of reference stabilized human blood for lymphocyte immunophenotyping quality control in flow cytometry

The development of automated methods and normative rules, as well as the de pendence of some therapeutic approaches on lymphocyte subsets counts, has l ed to the appearance of calibration reagents. Such reagents are expected to perform equally well in very different settings. We developed a multicente r trial to evaluate the performance of a new quality control reagent, i.e., stabilized blood to be used in immunophenotyping laboratories. Aliquots of the same batch of stabilized blood were shipped to 45 French and Belgian l aboratories on a Monday and had to be tested for percentages and absolute c ounts of at least CD3-, C04-, and CD8-positive lymphocytes on 4 consecutive days. The percentages and absolute counts obtained on each assay were reco rded, as well as the type of lysis used, the trademark of reagents, and the brand of flow cytometer. The mean values collected did not differ signific antly from those expected by the manufacturer. Absolute counts generated th rough one-step techniques displayed lower CVs. This new reagent therefore a ppears to be a robust product, liable to yield consistent results in the ar ray of different conditions represented by routine laboratories, and it cou ld be useful for quality control procedures. (C) 1999 Wiley-Liss, Inc.