Methods
We performed serial quantification of the PNH clone size in 38 samples using multiparameter flow cytometry. Granulocytes, monocytes and RBCs were gated using forward and side scatter as well as lineage-specific markers. The GPI-linked markers fluorescent aerolysin (FLAER), CD55 and CD59 were comparatively evaluated. We also evaluated CD16 on granulocytes and CD14 on monocytes. The sensitivity of detection by each marker was further defined by serial dilution experiments on a flow-sorted sample. Two patients had quantification of their GPI-negative clones before and after allogeneic BMT.