Apheresis is a process whereby special types of blood cells are collected from a patient’s vein. The types of cells collected by apheresis can be peripheral blood stem cells, donor lymphocytes or platelets. Apheresis is performed by placing intravenous (IV) access into veins of the arms or hands. For patients without large veins or those patients who are too small, a central line can be placed into one of the large veins of the chest or groin. Apheresis takes approximately four-five hours per day for one-three days, depending on the type and number of cells that need to be collected. During apheresis, blood is removed through one vein, then processed through the apheresis machine, where the cells of interest are removed. Thereafter, the remaining blood components are returned to the patient via the other vein. At St. Jude, apheresis is usually performed in the Blood Donor Room, which is the hospital department in which all blood products are collected.