Decreased deformability of the X-ray-irradiated red blood cells stored in mannitol-adenine-phosphate medium

X-ray irradiation of blood is an effective way to prevent transfusion-assoc iated graft-versus-host disease. Red blood cells (RBCs) from normal donors suspended in mannitol-adenine-phosphate (MAP) medium were irradiated with X -ray of 15 and 35 Gy in minimum dose. The change of deformability of the RB Cs during storage at 4 degrees C for 4 weeks was examined under shear stres s of 13-130 dyn/cm(2) using a rheoscope, in relation to the hematological a nd biochemical properties. (1) The deformability of RBCs was decreased duri ng the storage, and it was further decreased by the irradiation. In additio n, the number of undeformable RBCs against a given shear stress increased a fter the irradiation. (2) The cell volume gradually decreased, while the in tracellular hemoglobin concentration increased. These changes were accelera ted by the irradiation. The echinocytic transformation during the storage w as not accelerated by the irradiation. (3) The content of aggregated protei ns reducible with beta-mercaptoethanol in RBC membrane increased during the storage, but was not increased by the irradiation. Membrane lipid peroxida tion was not increased during the storage and by the irradiation. (4) Leaka ge of potassium ions from RBCs during the storage was accelerated by the ir radiation. In conclusion, shear-induced deformation of RBCs stored in MAP m edium was impaired by X-ray irradiation, mainly due to dehydration caused b y excess leakage of potassium ions from RBCs.