The distribution of buoyant density of human erythrocytes in bovine albumin solutions

Several reports have appeared in the literature of the variation of "density" among different types of dispersed cells and of physical separations based upon this property. (1,2) Two general separation procedures have been used. Packed cell methods: cells are centrifuged from a suspension to form a viscous mass of packed cells, which is separated layerwise. Neutral density separations: cells are centrifuged in a dense liquid medium and are segregated into two fractions, one denser and one lighter than the suspending medium. With such methods the order of density of certain types of blood cells has been established. (3-5) It has also been shown that erythrocytes are heterogeneous in density and that young erythrocytes are less dense than old. (6-9)