- Lymphapheresis is done at enrollment and at 12 months. This is a procedure for collecting quantities of lymphocytes (white blood cells that are an important part of the immune system). Blood is collected through a needle placed in an arm vein and circulated through a machine that spins it, separating it into its components. The lymphocytes are removed and the rest of the blood (red cells, platelets and plasma) is returned to the body through the same needle or another needle placed in the other arm.