PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA CLONE IN BONE-MARROW OF PATIENTS WITH PANCYTOPENIA

The lack of glycosylphosphatidylinositol (GPI)-anchored membrane prote ins such as decay-accelerating factor (DAF) and CD59 on blood cells ha s a diagnostic value in paroxysmal nocturnal hemoglobinuria (PNH). Bec ause PNH often develops in patients with aplastic anemia (AA), we atte mpted to detect a PNH clone in the bone marrow (BM) of patients with A A and pancytopenia before affected cells were evident in the periphera l blood (PB). We used flow cytometry with monoclonal antibodies agains t DAF and CD59 for the detection of the clone. Affected cells were obs erved in the BM of 3 of 7 patients with AA and 1 of 3 patients with pa ncytopenia of unknown origin, but not in their PB. All 8 patients with apparent PNH had affected cells in their BM and PB. On the basis of t he early appearance of the PNH clone in the BM, a prospective 4-month follow-up study of the PB cells was performed, The study showed the re lease of affected mature cells first in granulocytes, then in monocyte s, and finally in lymphocytes. Ham's test was positive before affected erythrocytes were detected by flow cytometry. Our findings indicate t hat detection of the PNH clone in BM could be predictive of the develo pment of PNH in patients with AA and pancytopenia. (C) 1995 by The Ame rican Society of Hematology.