Physical properties of red cells as related to effects in vivo. II. Effect of thermal treatment on rigidity of red cells, stroma and the sickle cell.

I T HAD BEEN ESTABLISHED by previous observations”2 that heating normal human red blood cells increases their osmotic and mechanical fragiities, and results in their sequestration in the spleen37 and liver.8 Human erythrocytes undergo budding, and the heated red cells subdivide into fragments having a decreased ratio of surface volume and increased osmotic fragility.’ Kimber and Lander8 have shown that human red cells heated for only 10 minutes (min. ) at 50 C. had a shortened survival and were sequestered by the spleen but not the liver. In a splenectomized normal subject, such cells had a longer survival. They also described cells that were spheroidal but had decreased osmotic fragility. More prolonged heating produced increased osmotic fragility and sequestration by spleen and liver.8 In dogs, cells with an increased osmotic fragility were rapidly removed when reinjected into the animal.’ There was hemoglobinemia and hemoglobinuria. Similar results were observed in patients with severe thermal burns in whom it was demonstrated2 in vivo that bizarre-shaped microspherocytes were circulating immediately following the thermal injury. These patients, too, had hemoglobinemia and hemoglobinuria and their red cells displayed increased osmotic and mechanical fragiities. A direct effect between the degree and duration of heating on the osmotic fragility has been demonstrated.’ In this report, human and dog red cells were heated to compare the morphologic changes in the two species. Observations were made on the resistance of heated red cells to packing by centrifugal force, flow through microfilters, and on the viscosity. The osmotic fragility, glucose metabolism and changes in cell cholesterol of blood heated at 37.5 C. and 49 C. were studied. A temperature of 49 C. was selected arbitrarily as a standard for treatment of red