Leukapheresis Collection of large numbers of white blood cells Whole blood is collected through a needle in an arm vein. The blood circulates through a machine that separates it into its components. The white cells are removed and the rest of the blood is returned to the body, either through the same needle used to draw the blood or through another needle in the other arm. (Alternatively, patients will 100 cc (about 7 tablespoons) of blood drawn.);