- Lymphapheresis: Patients undergo this procedure for collecting large numbers of white blood cells twice - once at the beginning of the study and again after 6 months. Blood is removed through a needle in an arm vein and flows through a machine that separates it into its components by centrifugation (spinning). The white cells and plasma are removed and the red cells and platelets are returned to the patients through the same needle or through another needle in the other arm.