Sterile, medium scale age fractionation of human red blood cells.

After sterile removal of white blood cells and the majority of platelets from blood in a regular transfusion bag, the remaining red blood cells were separated under sterile conditions into a relatively young and a relatively old fraction. Making use of the different densities of old and young red blood cells, the separation occurs in a double transfusion bag by centrifugation, after the cells have been carefully layered on top of Percoll of "tailor-made" density. The successful results of this simple and inexpensive technique are assessed by comparing the creatine concentration and the acetylcholinesterase activity in both fractions. Thus, this medium scale fractionation technique yields hundreds of ml of sterile, young red blood cells.