The Population of Paroxysmal Nocturnal Hemoglobinuria Neutrophils Deficient in Decay -

In patients with paroxysmal nocturnal hemoglobinuria (PNH) the RBCs, neutrophils (PMNsh monocytes, and platelets derived from the abnormal clone are deficient in the complement-regulatory protein decay-accelerating factor (DAF). RBC acetyicholinesterase (AChE) and leukocyte alkaline phosphatase (LAP) activities are also characteristically low. DAF, AChE, and LAP are known to be anchored within cell membranes to glycophospholipidcontaining phosphatidylinositol (P1). Because PNH progenitors contain DAF that appears to be lost with maturation. it has been proposed that this disorder results from abnormal tethering of these and possibly other proteins to membrane P1. We were puzzled, therefore, that our two PNH patients consistently had normal LAP levels. Consequently,