Studies on the destruction of red blood cells. IX. Quantitative methods for determining the osmotic and mechanical fragility of red cells in the peripheral blood and splenic pulp; the mechanism of increased hemolysis in hereditary spherocytosis (congenital hemolytic jaundice) as related to the functions of the spleen.

Abstract

Hereditary spherocytosis (congenital hemolytic jaundice) is an inherited disease entity characterized by chronic anemia, by increased hemolysis and erythropoiesis, and frequently by splenomegaly. The classic feature of this disease is the presence in the peripheral blood of red cells that are spheroidal in shape¹and that are unusually susceptible to hemolysis when suspended in hypotonic media.²These two abnormal prop- erties have been shown to be mutually interdependent, the increased osmotic fragility reflecting the fact that the surface membrane of the erythrocyte is reduced in size relative to its volume,* with the result that its capacity to swell before reaching the rupture point is reduced. Also, these cells are abnormally susceptible to trauma, having an increased "mechanical fragility." Moreover, when blood from these patients is incubated at 37.5 C there occurs a pronounced increase in the osmotic and mechanical fragility of the red cells which surpasses to a