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CD4 Cell Count: A Critical Tool in the Human Immunodeficiency Virus Response

Measuring CD4 cell count was the first laboratory test used for HIV patient care and has been essential to monitoring the clinical risk of opportunistic disease and death. More recently, however, it has been one of the most contentious laboratory tests in the HIV response. This is due to that fact that CD4 cell counts have been used to support a range of clinical decisions—when to start ART, which medication to use, and how to predict viral suppression and much less often to decide when opportunistic infection diagnostics and prophylactics should be administered. The more recent monitoring uses have fallen away as practice has changed with new evidence, better drugs, and the availability of…

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 What is CD4 & Why is it Important?

CD4 is a protein on the surface of T helper cells, a subset of T cells and play an important part in the body’s immune system. These white blood cells circulate throughout the body to find and destroy bacteria, invading organisms - and viruses. In the case of HIV, knowing the number of CD4 cells in the body is a good indicator of the severity of HIV infection. People who have low CD4 counts - below 200 - are at very high risk of opportunistic infections.

Articles of Interest

About Your Viral Load and CD4 Cell Count

The amount of HIV in your blood is called “viral load.” Viral load shows how fast HIV is reproducing in your body – the lower your viral load, the better. Your “CD4 cell count” measures the health of your immune system. The higher it is, the better your body can fight infections.

Are CD4 counts still useful in the 'treat all' era?

The researchers concluded that while there is very limited benefit to ongoing CD4 monitoring if people have CD4 counts above 200 at the time they start treatment, baseline CD4 cell tests remain essential to identify people with advanced disease.

Can I Boost my CD4 Count?

The only reliable way to increase CD4 cell count over time is with HIV treatment - antiretroviral therapy (ART). This treatment is recommended for those who are HIV positive - no matter how long they may have the virus, and it ultimately works towards keeping the viral load low and CD4 count high.

CD4 Cell Count

There are two main types of T-cells: T-4 cells (CD4) are “helper” cells that lead the attack against infections. T-8 cells (CD8) are “suppressor” cells that end the immune response. CD8 cells can also be killer cells that kill cancer cells and cells infected with a virus. HIV most often infects CD4 cells. The genetic code of the virus becomes part of the cells. When CD4 cells multiply to fight an infection, they make more copies of HIV.

Expanding roles for CD4+ T cells in immunity to viruses

Viral pathogens often induce strong effector CD4+ T cell responses that are best known for their ability to help B cell and CD8+ T cell responses. However, recent studies have uncovered additional roles for CD4+ T cells, some of which are independent of other lymphocytes, and have described previously unappreciated functions for memory CD4+ T cells in immunity to viruses.

New Cell Test for AIDS Patients Could Be Key for Poor Nations

A rapid, portable test to measure immune cells in people with the AIDS virus soon could be available for less than $1 in poor countries, making it easier to identify patients most in need of medicines.

Reliability and validity of self-reported CD4 lymphocyte count and viral load test results in people living with HIV/AIDS

Self-reporting is a common, convenient, and inexpensive method for collecting health status information in HIV/AIDS research, but the reliability and validity of these data remain suspect.

What is T-cell or CD4 count?

The T-cell or CD4 count is measuring your immune system, how strong your immune system is and you want that to be high. A normal T-cell count is usually between the area of about 450 and 1,100. That being said, some people, their set point may be different. So some people always live around 500 T-cells. No matter if they’re on medications, off medications, HIV negative, positive, it doesn’t matter. Some people live around 1,100. The important part is not to compare yourself to other people all the time.

What my CD4 count and viral load tell me

Your CD4 count tells you how your immune system is doing. The higher the number, the better. CD4 cells are the “bosses” of the immune system. They lead the fight against invading germs and viruses. Your CD4 count tells you how many CD4 cells you have in a cubic millimetre (mm3) of blood. A normal CD4 count is anywhere from 500 to 1,500. A low CD4 count puts you at greater risk of getting sick. Once you start HIV treatment, your CD4 count will likely rise, and many people on HIV treatment have normal CD4 counts.

Resources

AIDSMap

Your CD4 cell count gives you an indication of the health of your immune system – your body’s natural defence system against pathogens, infections and illnesses.

StatPearls

CD4 T cells are human helper T cells that express cluster determinant 4 (CD4) molecules. The CD4 molecule is a member of the immunoglobulin family and primarily mediates adhesion to major histocompatibility complex molecules. CD4 T cells are selectively targeted and infected by HIV. HIV proliferates rapidly during acute infection leading to high levels of viremia and rapid impairment and death of CD4 T cells.