What are CD4 Cells?CD4 cells are white blood cells that play an important role in the immune system. Your CD4 cell count gives you an indication of the health of your immune system, your body’s natural defense system against pathogens, infections and illnesses. CD4 cells are sometimes also called T-cells, T-lymphocytes, or helper cells.
CD4 CountA CD4 count is a lab test that measures the number of CD4 T-lymphocytes (CD4 cells) in a sample of your blood. In people with HIV, it is the most important laboratory indicator of how well your immune system is working and the strongest predictor of HIV progression. The CD4 count of an uninfected adult/adolescent who is generally in good health ranges from 500 cells/mm3 to 1,500 cells/mm3. A very low CD4 count (less than 200 cells/mm3) is one of the ways to determine whether a person living with HIV has progressed to stage 3 infection (AIDS).
HIV and CD4HIV uses CD4 cells to multiply (make copies of itself) and spread throughout the body. This process is called the HIV life cycle. So, during your regular check-ups, your HIV doctor will want to know your CD4 count to help keep track of how healthy you are and whether the virus has progressed in your body. Your CD4 count is also used to help you and your HIV doctor decide when to start AntiRetroviral Therapy (ART). ART involves taking a combination of HIV medicines every day. It prevents HIV from multiplying and destroying your infection-fighting CD4 cells. ART cannot cure HIV, but it can help you live a longer, healthier life and reduce your risk of HIV transmission. ART is recommended for everyone with HIV, but the urgency to start ART is greater in people with low or rapidly falling CD4 counts. After you start ART, your HIV doctor will use your CD4 count as one way to check how well your medication is working. Your HIV doctor will also monitor your CD4 count to determine whether it has fallen to a level at which you might be at risk for certain opportunistic infections. In that case, your HIV care provider may prescribe some additional medications to prevent other infections.
Other Factors Affecting your CD4 CountIt tends to be lower in the morning and higher in the evening. Fatigue and stress can skew test results. An infection like the flu, pneumonia, or a herpes simplex virus (including cold sores) can make your CD4 count go down for a while. Getting a vaccination can also change it while your body learns how to fight that sickness. Your CD4 count will go way down when you’re having chemotherapy for cancer. To get the best and helpful results for your CD4 count, try to:
- Use the same lab each time.
- Have your tests done at the same time of day.
- Before getting tested wait for at least a couple of weeks if you have been sick or if you recently got a shot.