Donor lymphocyte infusion. Lymphocytes (a type of white blood cell) from the blood of a donor are given to a patient. (Panel 1): Blood is taken from a vein in the donor’s arm. The blood flows through an apheresis machine that removes the lymphocytes. The blood is then returned to the donor through a vein in the other arm. (Panel 2): The patient receives the lymphocytes through a catheter in the chest.