Why The Test Is Performed A count of the T cells may be helpful in the diagnosis of immunodeficiency diseases and lymphocytic diseases. It is also used to monitor the response to therapy for these type of diseases.
Lymphocytes are white blood cells that are part of the immune system.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding . Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. In the laboratory the white blood cells are separated from other blood cells.