Understanding CD4 Cells and CD4 Cell Tests
Your immune system protects your body by fighting germs and infections. White blood cells are an important part of your immune system. HIV infects and destroys a type of white blood cell called a CD4 cell (sometimes called a T-cell).
As the immune system loses CD4 cells, it becomes weaker and is less able to fight off germs. When it loses a large number of CD4 cells, people living with HIV (HIV+) become at risk of getting AIDS-related opportunistic infections (OIs), which are infections that can cause serious illness or death.
The number of CD4 cells you have gives a picture of the health of your immune system. A normal CD4 cell count is about 500 to 1,500 cells per cubic millimeter of blood (a cubic millimeter is a very small amount, about one drop). The number of CD4 cells a person has -- their "CD4 count" -- usually falls as HIV disease progresses. Your CD4 cell count can help your health care provider tell whether your HIV disease is progressing, whether you should start HIV treatment, and whether the treatment you are taking is working well.
Without HIV treatment, HIV infects more and more cells. In most HIV+ people, this causes the CD4 count to go down about 50 to 100 cells per year. As the CD4 count goes down, an HIV+ person becomes more likely to develop OIs and cancers.
The US Department of Health and Human Services (DHHS) treatment guidelines now recommend treatment for all people living with HIV, no matter what their CD4 count.
The DHHS panel's recommendation to begin treatment with a CD4 count above 500 is a "moderately strong" recommendation based on expert opinion and not on data from clinical trials. The panel's recommendation to begin treatment with a CD4 count under 500 is based on the results of well-designed studies.
[Note: Because the panel's expert opinion is not based on results from randomized controlled trials, which are often considered the 'gold standard' for providing evidence, there is some debate about the DHHS panel's new recommendation to begin treatment with a CD4 count above 500. In other words, while some experts agree that the current level and quality of evidence supports treatment above 500, other experts do not.]
The DHHS treatment guidelines state:
Many people see their CD4 counts increase when they start effective HIV treatment. If the drugs succeed in slowing or stopping HIV, fewer new CD4 cells will be infected and your CD4 count may go up. However, your CD4 count can also go down again if you stop taking your HIV drugs correctly, or if your HIV becomes resistant to the drugs. Along with your viral load, your CD4 count is a very valuable tool for monitoring your HIV disease and how well your HIV drugs are working.
This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with TheBody.com to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from TheBody.com or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.
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