Complement-sensitive red cells in aplastic anemia.

In view of the clinical association of aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH), the complement-dependent lysis of the youngest red cells of AA patients was studied. A complement-sensitive population of young red cells was found in five of six patients with AA. These cells were rapidly cleared from the circulation and were undetectable in the oldest cell fraction. Such cells were not found in normal controls or in a variety of hematologic disorders, with the exception of PNH. This study suggests that in most patients with AA, even without any clinical manifestations of PNH, there is a population of dyserythropoietic, short-lived complement-sensitive cells.