B and T cell screen is a laboratory test to determine the amount of T and B cells (lymphocytes) in the blood.
How the Test is Performed
Blood could also be obtained by capillary sample (fingerstick or heel stick in infants).
After the blood is drawn, it goes through a two-step process. First, the lymphocytes are separated from other blood parts. Once the cells are separated, identifiers are added to distinguish between T and B cells.
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
Your provider may order this test if you have signs of certain diseases that weaken the immune system. It may also be used to distinguish between cancerous and noncancerous disease, particularly cancers that involve the blood and bone marrow.
The test may also be used to determine how well treatment for certain conditions is working.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal T and B cell counts may suggest a possible disease. Further testing is needed to confirm a diagnosis.
An increased T cell count may be due to:
- Cancer of white blood cell called a lymphoblast (acute lymphoblastic leukemia)
- Cancer of white blood cells called lymphocytes (chronic lymphocytic leukemia)
- A viral infection called infectious mononucleosis
- Blood cancer that starts in the plasma cells in the bone marrow (multiple myeloma)
- Syphilis, an STD
- Toxoplasmosis, an infection due to a parasite
An increased B cell count may be due to:
- Chronic lymphocytic leukemia
- DiGeorge syndrome
- Multiple myeloma
- Waldenstrom macroglobulinemia
A decreased T cell count may be due to:
- Congenital T-cell deficiency disease, such as Nezelof syndrome, DiGeorge syndrome, or Wiskott-Aldrich syndrome
- Acquired T-cell deficiency states, such as HIV infection or HTLV-1 infection
- B cell proliferative disorders, such as chronic lymphocytic leukemia or Waldenstrom macroglobulinemia
A decreased B cell count may be due to:
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
E-rosetting; T and B lymphocyte assays; B and T lymphocyte assays
Liebman HA, Tulpule A. Hematologic manifestations of HIV/AIDS. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 157.
Riley RS. Laboratory evaluation of the cellular immune system. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 45.
Review Date 12/24/2020
Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.