B and T cell screen
Key points
- A test that makes a quantitative measurement of T and B lymphocytes in the blood.
- Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand.
- How the test will feel When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation.
- This test is performed to aid your health care provider in the diagnosis of immunodeficiency diseases.
Alternative names
Direct immunofluorescence; E-rosetting; T and B lymphocyte assays; B and T lymphocyte assays
Definition
A test that makes a quantitative measurement of T and B lymphocytes in the blood.
How the test is performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to cause the vein to swell with blood.
A needle is inserted into the vein, and the blood is collected in air-tight vials or a syringe. During the procedure, the band 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.
Blood could also be obtained by capillary sample (fingerstick, or heelstick in infants).
After the blood is drawn it goes through a two step process. First, the lymphocytes are separated from other blood elements. Once the cells are separated, identifiers are added to distinguish between T and B lymphocytes. The E-rosetting test identifies T cells and direct immunofluorescence is used to identify B cells.
How to prepare for the test
No alteration in diet is necessary for this test.
Inform your health care provider of anything in your life that might affect your T and B cell count, such as:
- X-rays
- chemotherapy
- surgery
- steroid therapy
- stress
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is performed to aid your health care provider in the diagnosis of immunodeficiency diseases. It may also be used to distinguish between benign and malignant lymphocytic disease. Finally, this test may be performed to monitor your response to therapy.
Normal Values
Values vary from laboratory to laboratory, and depend on testing technique, but typically, T cells comprise 68% to 75% of total lymphocytes and B cells 10% to 20%.
What abnormal results mean
Abnormal T and B cell counts suggest possible diseases. Further testing is indicated to confirm any of the suggested diagnosis.
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.