Monitoring of CD59 expression in paroxysmal nocturnal hemoglobinuria treated with danazol

We describe a 52-year-old man with paroxysmal nocturnal hemoglobinuria (PNH) and a moderate transfusion requirement. Prior to and during sequential therapy with androgen (metenolone), glucocorticoid, and danazol, we evaluated CD59-negative expression (PNH clone) in red blood cells, neutrophils, lymphocyte subsets, and bone marrow (BM) CD34(+) cells. Although androgen and glucocorticoid were not effective for recovery of blood cell counts, the hemoglobin and platelet levels increased immediately after the therapy with danazol and the patient became transfusion independent. However, neither the serum level of LDH nor the percentage of PNH clone in each cell lineage, including BM CD34(+) cells, decreased. The number of nucleated cells in BM increased drastically after the start of danazol. These findings suggest that the efficacy of danazol was not only due to the impediment of hemolysis but also due to stimulation of PNH clone proliferation in BM.