What is CD4 and to serving the Test CD4 cells?

Representation of a CD4 cell

What are the CD4 cells?

blood-75301CD4 is a molecule that is expressed on the surface of some T cells, macrophages, monocytes and in the dendritic cell. It is a monomeric glycoprotein of 59kDa that contains four immunoglobulin-like domains (wikipedia - CD4)

CD4 cells are a type of lymphocytes (white blood cell). They are an important part of the immune system. CD4 cells are sometimes called T cells. There are two main types of T cells. T-4 cells, also called CD4, are "Auxiliary Cells". They led the attack on infections. T-8 (CD8 cells) are "suppressor cells" of the immune response. CD8 cells can also be "Killer" (killer) cells that kill cancer cells and virus-infected cells.

These cells look for and characterize other cells and infectious agents by specific proteins on the surface of the cell. A T-4 cell is a T cell with CD4 molecules on its surface. This type of T cell is also called the "Positive Cell" cell, CD4 or CD4.


HIV most often infects CD4 cells. The virus becomes part of the cells and, when multiplied to fight an infection, they make more copies of HIV.

When someone is infected with HIV but has not started treatment, the number of CD4 cells is decreasing. This is a sign that the immune system is being weakened. The lower the CD4 cell count, the greater the likelihood of this person becoming ill.

There are millions of different families of CD4 cells. Each family is designed to fight a specific type of germ. When HIV decreases the number of CD4 cells, some of these families can be eradicated. You may lose the ability to fight off germs whose families have been designed. If this happens, you can develop a opportunistic infection (See Fact Sheet 500).


A small sample of blood is taken. Blood is tested for counts of various cell types. CD4 cells are not counted directly. Instead, the lab does a calculation based on total white blood cells and the proportion of cells that are CD4. Therefore, the CD4 count is not accurate.

The current treatment (see Sheet of fact 404) suggests monitoring CD4 through testing every 3 to 6 months when initiating antiretroviral therapy (ART, see Sheet of fact 403). Since the treatment increases the levels of CD4 to high levels, the test should be done every 6 to 12 months.

What are the factors influencing CD4 cell count?

The value of CD4 cells varies around batches. Time of day, fatigue and stress can affect test results. It is best to have blood drawn at the same time of day for each cell testPay 937884 CD4 and to use the same laboratory.
Infections can have a major impact on the CD4 cell count. When your body fights an infection, the number of white blood cells (lymphocytes) rise. And the CD4 and CD8 cell count goes up too high. Vaccination may cause the same effects. Do not check your CD4 cells until a couple of weeks after recovering from an infection or being vaccinated.

As the test results are reported?

Tests of CD4 cells are usually reported as the number of cells in a cubic millimeter of blood or mm3. Normal counts are usually between 500 and 1600.

Because the CD4 cell count is so variable, some healthcare providers prefer to look at the percentage of CD4 cells. If your test reports 4% CD = 34%, which means that 34% of your lymphocytes were CD4 cells. This percentage is more stable than the number of CD4 cells. The normal range is somewhere between 30% and 60%. Different laboratories use different ranges. There are no guidelines for treatment of decisions based on percentages of CD4. However, a percentage of CD4 below 14 is a definition of AIDS.

A count of CD4 below 200 indicates severe damage to the immune system. It is a sign of AIDS in people with HIV infection. Although the percentage of CD4 may be a better predictor of progression of HIV disease than the CD4 count, the CDXUMUMX count is used to decide when to start treatment.

What do the numbers mean?

The CD4 cell count is a key measure of immune system health. The lower the count, the greater the damage caused by HIV. Those who have less than 200 CD4 cells or a percentage less than 14%, are considered to be AIDS patients according to the US Centers for Disease Control and also the National STD / AIDS and Viral Hepatitis Program of the Ministry of Health.

CD4 counts are used in conjunction with viral load to estimate how long someone will stay healthy. See Sheet of fact 125 for more information about the viral load test.

CD4 counts are also used to indicate when to start certain types of drug treatment:

When to start the drug to prevent opportunistic infections:
Most health care providers prescribe medications to prevent opportunistic infections at the following levels of CD4:
Less than 200: Pneumocystis pneumonia (PCP, see Sheet of fact 515)
Less than 100: toxoplasmosis (see Sheet of fact 517) and cryptococcosis (see Sheet of fact 503)
Less than 50: Mycobacterium avium complex (MAC, see Sheet of fact 514)

Monitoring of treatment success:
With the success of ART, CD4 counts can sometimes rise rapidly. Other times they may climb slowly. If the CD4 count is low when the TARV starts, the CDXUMUMX counts may not recover to normal levels. {Note from Translator, not to mention me, I quote Beatriz Pacheco and Beto Volpe, whose clinical records, if read by an unsuspecting physician, could at some point say that "these people are dead" the truth is that they waste, give , sell, lease, and spend health with the success of their treatments which, at the time of their respective beginnings, were not "very promising"]. In addition, if CD4 counts fall while you are on ART, it may be occurring failure and one of the reasons may be due to the maintain your treatment adherence in a Spartan way. Higher counts of CD4 are better. However, a normal CD4 count does not guarantee a normal immune system.

Continuous monitoring
The current treatment guideline (available in http://aidsinfo.nih.gov/guidelines) suggests that if a patient maintains the viral load undetectable, the CD4 count can be done once a year or even less frequently.


Now that people with AIDS live longer, there is more research into other causes of illness and death. These are non-AIDS-related causes of death, which include liver disease, non-AIDS-related cancer, and heart disease. Overall, these deaths are declining. However, the research shows a clear link between the low CD4 count and the risk of death.

Bottom line

Because they are an important indicator of the strength of the immune system, an information sheet of treatment guidelines in the US suggests that the CD4 count should be monitored every six to twelve months for people whose ART has worked to maintain a high level of CD4 cells.

Editor's note: In my last passage by the House of AIDS, my Medical (With "M" thus capital) passed me similar instructions and, although I have gone just a little upset with the government, I knew that Angela would not or under strong coercion and accepted peacefully. Editing the text now see that I was right about my considerations by the person who studied and has dedicated his life to keep me and about four other alive and healthy patients

Translated and edited by Claudio Souza the original Fact Sheet 124 CD4 Cell Tests in 06 April 2016 Reviewed by Mara Macedo