Lymphocytes are typically collected through a process called apheresis.
During apheresis, a patient lies on a bed or reclines in a chair while needles are inserted into each arm. Blood is drawn from one arm and circulated through an apheresis machine. This machine filters out the lymphocytes, along with some plasma, which keeps the cells suspended. The collected lymphocytes and plasma are then gathered in a special bag. The remaining blood components are returned to the patient through the needle in the other arm. This allows doctors to collect a large number of lymphocytes without significantly reducing the patient's overall blood volume.
