CD4 Lymphocyte Count

The CD4 lymphocyte count, also known as the CD4 cell count or T-cell count, is a medical test that measures the number of CD4 T cells (also called T helper cells) in a cubic millimeter (mm^3) of blood.

What are CD4 Cells?

CD4 cells are a type of white blood cell that plays a crucial role in the immune system. They help to coordinate the immune response by assisting other immune cells, such as B cells and cytotoxic T cells, to fight infections.

Purpose of the Test

The CD4 lymphocyte count is primarily used to monitor the health of individuals with HIV (Human Immunodeficiency Virus) infection or AIDS (Acquired Immune Deficiency Syndrome). The test helps to:

• Diagnose HIV infection and monitor its progression
• Evaluate the effectiveness of antiretroviral therapy (ART)
• Assess the risk of opportunistic infections and other complications associated with HIV/AIDS

How is the Test Performed?

The CD4 lymphocyte count is typically performed on a blood sample collected from a vein in the arm. The blood sample is then sent to a laboratory for analysis, where it is processed using a technique called flow cytometry.

Interpretation of Results

The results of the CD4 lymphocyte count are usually reported as a number of cells per cubic millimeter (mm^3) of blood. The normal range for CD4 cell count varies depending on factors such as age, sex, and laboratory methods, but generally falls between 500-1600 cells/mm^3.

In individuals with HIV infection, the CD4 cell count can be classified into several categories:

• Normal: >500 cells/mm^3
• Mild immunosuppression: 200-499 cells/mm^3
• Moderate immunosuppression: 100-199 cells/mm^3
• Severe immunosuppression: <100 cells/mm^3

Clinical Significance

A low CD4 cell count indicates a weakened immune system, making an individual more susceptible to opportunistic infections and other complications associated with HIV/AIDS. The CD4 lymphocyte count is used in conjunction with other tests, such as the viral load test, to monitor the progression of HIV infection and adjust treatment accordingly.