Lymphocyte Subset Enumeration CD3,CD4 ,CD8

What is CD4 and CD8 test?

This test has major utility in HIV infection for prognostication of the disease. It is essential to obtain baseline CD4 counts before starting HIV infection treatment. CD4 and CD8 test is done to assess the strength of immune system these patients. Serial monitoring is done to determine the stage, severity and outcome of the infection. It tells us about disease progression, predict for future complications and effectiveness of antiretroviral treatment. CD4/CD8 ratio may also be of help in monitoring chronic lymphocytic leukemia, hodgkin disease, aplastic anemia, neurological disorders like multiple sclerosis and myasthenia gravis and infections like infectious mononucleosis, other viral infections and sexually transmitted diseases. Apparently excess levels of CD4 positive cells may arise due to a congenital or acquired deficiency of CD8 positive cells and vice versa.

What is CD4 and CD8 markers?

CD4 and CD8 are T-lymphocyte antigens. CD4 is a biomarker for normal T-helper cells and CD8 for normal T-suppressor cells. Normally CD4 cells are more than CD8 cells and peripheral blood CD4/CD8 ratio is approximately 2:1 (range 1:1 to 3:1), while the normal bone marrow ratio is reversed at approximately 1:2. At any given point of time, T-cells co-expressing both CD4 and CD8 are undergoing thymic maturation or migration and are present at very low levels in normal circulation. This test helps in monitoring body’s T cell status and gives us a broad overview of an individual’s immune system. It looks at 2 types of lymphocytes simultaneously in a person’s body. CD4 cells play an important role in T-cell activation, fighting against infections, maintaining peripheral tolerance and preventing autoimmunity. CD8 cells help in combating cancer cells and other foreign invaders. CD4 cells are one of the important targets for HIV-Human immunodeficiency virus.

What is a good CD4 /CD8 ratio?

Biological reference range for CD4/CD8 RATIO is 0.39 - 3.02. If ratio is >1, it means your immune system is strong. This is per say a good ratio. In HIV infection, it is always advisable to calculate absolute values of CD4 and CD8. There is profound CD4 depletion in HIV infection which should not be reported as excess of CD8 levels. Depending upon the ratio, clinician will decide the treatment strategy to improve patient’s status. This ratio acts as guiding factor for treatment and future prognosis. Peripheral blood CD4 / CD8 ratio is reversed in HIV and this increases the risk for opportunistic infections and complications. Lower CD4 / CD8 ratio in non-HIV patients may be seen in bone marrow problem post-chemotherapy, anemia, nervous system disorders like multiple sclerosis and myasthenia gravis or any other chronic infections. Higher than normal ratio is seen in most of the major infections, viral infections and blood cancer / T cell lymphoproliferative disorders (LPDs).

What is a CD8 test?

CD8 test is a blood test done by Flowcytometry analysis. CD8 is a marker for normal T-suppressor cells. In this test, first the lymphocytes are separated from other white blood cells using CD45 gating. Then T lymphocytes expressing CD3 are separated out and subsequently absolute value and percentage of CD4 (Helper T) cells and CD8 (suppressor T) cells in a given sample is reported. Once all values are obtained, CD 4/CD8 ratio is calculated. Biological reference range for CD8% is 20.06 - 45.52% and absolute count is 218 – 1396 cells/uL.