Flow cytometric analyses of a whole blood sample from a representative patient with SCD stained with annexin V–FITC and glycophorin-A PE in the presence of either calcium or EDTA.

(A) Dot plot of forward size scatter versus glycophorin-A–PE fluorescence stained in the presence of EDTA. Regions R1 and R2 represent red-cell microvesicle–associated and intact-erythrocyte–associated events, respectively. (B) Histogram of annexin V–FITC fluorescence of intact erythrocytes stained in the presence of EDTA. (C) Histogram of annexin V–FITC fluorescence of red cell vesicles stained in the presence of EDTA. Gate M2 represents annexin V–FITC–positive events. (D) Dot plot of forward size scatter versus glycophorin-A–PE fluorescence stained in the presence of calcium. Regions R1 and R2 represent red-cell microvesicle–associated and intact erythrocyte-associated events, respectively. (E) Histogram of annexin V–FITC fluorescence of intact erythrocytes stained in the presence of calcium. (F) Histogram of annexin V–FITC fluorescence of red cell vesicles stained in the presence of calcium. Gate M2 represents annexin V–FITC–positive events.