Quality of hematologic recovery in patients with aplastic anemia following cyclosporine therapy.

To evaluate quality of hematologic recovery in aplastic anemia (AA) patients treated with cyclosporine A (CyA), we examined polymorphonuclear leukocytes (PMNCL) from 25 AA patients for clonality and glycosyl-phosphatidylinositol (GPI)-anchored membrane protein expression. Using three different X-linked gene probes, we failed to detect clonal hematopoiesis in seven CyA-responsive female patients. Clonal hematopoiesis was detected in two of six female patients refractory to CyA therapy, although one of these two patients had shown monoclonality before therapy. Flow-cytometric analysis revealed a normal expression of GPI-linked membrane proteins, including CD55, CD59, and CD16 on PMN in all patients treated with CyA, irrespective of response, except for one patient who had a small proportion of GPI-anchored membrane protein-negative cells before therapy. The proportion remained unchanged 41 months after hematologic recovery following CyA therapy. These findings suggest that successful therapy of AA with CyA may not be associated with a significant risk of developing late clonal complications, such as paroxysmal nocturnal hemoglobinuria (PNH) and myelodysplasia.