DEFICIENCY OF PHOSPHOTIDYLINOSITOL-LINKED MEMBRANE-PROTEINS ON ERYTHROCYTES OF DIFFERENT SUBPOPULATIONS IN PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA

The surface phosphatidylinositol (PI)-linked proteins on membrane of p aroxysmal nocturnal hemoglobinuria (PNH) erythrocytes (PNHE) was analy sed by a flowcytometer (FACS 420). It was found that the loss of acety lcholinesterase (AchE) and decay accelerating factor (DAF), two PI-lin ked proteins, from cell membrane of PNHE was not synchronous. The hemo lysis rates of DAF (-) and AchE (-) PNHE were much higher than that of mixed population in cobra-venom factor (CoF) lysis test. Intact PNHE remaining after CoF lysis had relatively lower immunofluorescent label ing rate of AchE on membrane in comparison with normal erythrocytes. I t implied that this subpopulation, in spite of being insensitive to co mplement lysis, was still abormal in terms of the amount of PI-linked protein on cell membrane. When these intact PNHE remaining after CoF l ysis were incubated with activated polymorphonuclear leukocytes (PMN) for three hours, immunofluorescent labeling of AchE on PNHE was promin ently decreased. This indicated that reactive oxidants released from a ctivated PMN might injure PI-linked proteins.