Use of aerolysin to detect a minor population of PNH cells in patient with aplastic anemia. Two-color histogram of peripheral blood cells stained with MoAb directed against CD59 antigen (FITC) and MoAb directed against glycophorin-A (PE) before (A) and after (B) exposure to aerolysin (5 × 10⁻⁹ mol/L for 15 minutes). Axis represent log red (PE) or log green (FITC) fluorescence intensity.