Equilibrium density gradient analysis of erythrocytes from normal humans and patients with Duchenne muscular dystrophy.

Human red blood cells were fractionated by centrifugation in a continuous Ficoll/Triosil density gradient and the density distribution was determined by scanning the gradient in situ. Variation of some of the conditions used showed that erythrocyte mean cell density is very sensitive to the type of anticoagulant and washing system employed. A population study of mean cell density showed no significant difference between males and females and no correlation with age. Patients with Duchenne muscular dystrophy showed no significant difference from normals in mean cell density but an almost sevenfold increase in the variance. This may explain the disparate findings of different workers.