Aplastic anaemia and paroxysmal nocturnal haemoglobinuria: a study of the GPI-anchored proteins on human platelets.

Twenty-six consecutive patients with acquired aplastic anaemia (AA) and nine patients with de novo paroxysmal nocturnal haemoglobinuria (PNH) were included in this study. In these 35 patients a GPI-anchored molecule defect at the platelet surface was investigated by flow-cytometry. Platelets from eight out of the nine patients with de novo PNH were found to be deficient for the GPI-anchored molecule CD55, CD58 and CD59. We also detected a GPI-anchored molecule defect on monocytes, granulocytes, and erythrocytes in all patients with de novo PNH. Among the 26 AA patients, a GPI defect was detected on platelets in five patients. Interestingly, these five patients were also found to have a GPI-anchored molecule defect on erythrocytes, whereas in 10 patients the GPI-anchored molecule defect was only detected on monocyte and polymorphonuclear (PMN) cells.