The expression of CD59 and CD55 proteins in RBCs and MNCs. RBCs and MNCs from patients (represented in the figure by patient 5119), carriers of the Cys89Tyr mutation, and a normal control were stained with anti–CD59-FITC and anti–CD-55-PE. Top panel shows RBCs costained with anti–CD59-PE and anti–CD-55-FITC. The percentages of CD-59⁺ cells are indicated in the right top quadrant together with mean fluorescence (MF). Bottom panel shows MNCs (left) of patient 5119 and RBCs of patients 2962 and 5078 (middle and right) stained for anti–CD59-PE.