Erythrocyte vesiculation in paroxysmal nocturnal hemoglobinuria.

Red blood cells from patients with paroxysmal nocturnal hemoglobinuria (PNH) were found to be liable to vesiculate, as demonstrated by both DMPC liposome- and CaCl2-induced vesiculation and measured in terms of acetylcholinesterase activity and 3H-inositol radioactivity in the supernatant. Membrane proteins released from the cells during vesiculation included several constituents with molecular weights identical to those of some complement regulating factors (e.g. DAF) which play an essential role in complement-mediated hemolysis. Red blood cells from both normal and PNH patients showed decreased deformability after vesiculation. Liability to vesiculate and the consequential loss of certain essential membrane proteins and decreased deformability might be a factor contributing to the mechanism of hemolysis in PNH.