2. Apheresis: Before beginning treatment and at various times before and after chemotherapy, patients undergo apheresis to collect white blood cells for later re-infusion at the time of immunizations and to evaluate the body's response to the vaccines. For this procedure, blood is collected through the central venous catheter and circulated through a machine that separates the white cells from the rest of the blood. The white cells are removed and frozen for later use. The rest of the blood is returned to the patient through the catheter.