Diagnosis of Paroxysmal Nocturnal Hemoglobinuria (PNH) by the REDQUANT and the CELLQUANT kits

Background : Paroximal nocturnal hemoglobinuria (PNH) is a disorder of the pluripotent stem cells resulting in a deficient expression of membrane-bound GPI-anchored proteins in different cell types. We evaluated REDQUANT and CELLQUANT kits (Biocytex, Marseille, France) for PNH test. Methods : Seventy patients with peripheral blood cytopenia and 16 healthy controls were studied. RBCs and granulocytes were tested for CD55 and CD59 expression using the REDQUANT and CELLQUANT kits and an Epics XL flow cytometer. According to the manufacturer’s instruction, results were interpreted abnormal when more than 3% of cells were deficient in the expression of CD55 or CD59, and a test was considered positive for PNH if three of the four markers tested were abnormal. Results : The percentage of CD55/CD59 deficient RBCs and granulocytes was 0.3/3.1 and 3.5/ 10.0, respectively, in the patient group, and 0.1/1.0 and 0.3/9.7, respectively, in the control group. PNH was diagnosed in three patients who had a deficiency in the expression of three or four antigens; two other patients showed a deficiency in two antigens. There were many who had CD59 deficiency only: on granulocytes in 30 patients and 11 controls, and on RBCs in 6 patients and 2 controls. One patient had CD55 deficient granulocytes. Conclusion : The REDQUANT/CELLQUANT kit is a standardized method and does not require normal samples as the control, but one should be cautious in interpreting the results showing CD59 expression on granulocytes.