Proaerolysin flow-FISH. (A) Cow cells (R1 in Ai,Avi) can be distinguished from human diploid cells (R2 in Ai) based on PI staining. Lymphocytes (R3 in Aii) and granulocytes (R4 in Aii) were discriminated within diploid cells (R2 in Ai) based on size and granularity (Aii). Granulocytes can be separated into proaerolysin-positive and -negative cells (R5 and R6, respectively, in Aiii). This analysis was performed with (dark-gray peaks in Aiv-vi) and without (light-gray peaks in Aiv-vi) FITC-labeled PNA probes in order to allow subtraction of autofluorescence. (B) Scatter plots of the telomere length measurements of 14 GPI⁺ and 16 GPI^– granulocyte populations determined by proaerolysin flow-FISH in 16 patients with PNH and 22 age-matched healthy donors (HD). The horizontal lines represent the mean values of each group.