Flow-cytometric assessment of paroxysmal nocturnal hemoglobinuria clones in pediatric bone marrow failure syndromes

ABSTRACT

Patients suffering from bone marrow failure might develop various clonal complications, one of which is paroxysmal nocturnal hemoglobinuria [PNH]. We investigated the frequency of development of PNH in acquired aplastic anemia and Fanconi anemia using sensitive flow cytometric method, aiming to detect CD59 deficient expression on granulocytes. We found abnormal expression of CD59 [i.e. PNH clones] in 30.6% of the studied cases. All of them were PNH negative by the less sensitive laboratory methods [Ham's test]. Clinical and laboratory comparison revealed statistically significantly high mean corpuscular volume [MCV=105 +/- 10] in PNH positive patients, while PNH negative patients [MCV was 91 +/- 23. P-value=0.013]. The total leucocytic count was significantly lower in PNH positive' patients [2.9 +/- 1.4] when compared with PNH negative [4.6 +/- 2, P-value = 0.01]. Subgroup analysis revealed that MCV was higher in PNH positive acquired aplastic anemia [AAA] in support to previously stated hypothesis about the relationship between immune etiology and PNH in AAA. Fanconi PNH positive patients were lower in their total leucocytic count indicating more severe form of the disease. In conclusion, we found that Flow cytometric analysis is superior to the Ham test in diagnosis of paroxysmal nocturnal hemoglobinuria. Further follow up of patients with PNH positive clones and their response to various therapeutic modalities is recommended