High-sensitivity flow cytometric analysis of erythrocytes. By careful gating and by using dual-color flow cytometry, GPI-deficient cells that comprise less than 1% of the total erythrocyte population can be reliably and reproducibly demonstrated (B-C).²  Using this technique, GPI-AP–deficient cells are not identified in the peripheral blood of the controls (volunteer donors; A). A combination of FITC-labeled anti-CD55 and anti-CD59 was used along with phycoerythrin (PE)–labeled anti–glycophorin A for the dual staining. These data were kindly provided by Dr Shinji Nakao and Dr Chiharu Sugimori, Kanazawa University, Japan, and are used with their permission. Illustration enhanced by A. Y. Chen.