The Initiation and Enhancement of Human Red Cell Lysis by Activators of the First Component of Complement and by First Component Esterase; Studies Using Normal Red Cells and Red Cells from Patients with Paroxysmal Nocturnal Hemoglobinuria*

Abstract

The addition of polyinosinic acid (poly I) to a suspension of red cells from patients with paroxysmal nocturnal hemoglobinuria (PNH) in undiluted normal human serum results in pronounced stimulation of red cell lysis. Other activators of the first component of complement CC''1) such as dextran sulfate, streptokinase, and aggregated gamma globulin, as well as activated C''1 ana C''1 esterase, can enhance PNH red cell lysis in a similar fashion. Dextran sulfate can also induce normal red cell lysis. These hemolytic systems are presumed to result from the evolution in the fluid phase of hemolytically active, late-acting, labile complement components, capable of injuring red cell membrane despite the lack of an antibody coat. The observation that "indifferent" complement activation can result in red cell damage may be pertinent to concepts regarding the pathogenesis of certain acquired hemolytic anemias in man.