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CD 4 COUNT

What is CD 4 Count?

CD4 cell is a lymphocyte cell called a "Helper Cell". You may be more familiar with the term "white blood cells" on your full blood count report. Under the total white blood cells, there are subdivisions of white blood cells and one of them is called Lymphocyte.

CD4 cells are identified by their receptor on the cell surface. It is similar to how we identify people from their skin colour. If you are yellow-brown skin means you are of Mongolian (Asian) descent, black is Aethiopian (African) and white means you are Caucasians,

CD4 cells have a "skin-called-CD4" on the surface and that identifies that it is Helper-Lymphocyte.

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What is the function of CD4?

CD4 cells are used to signal to the other body's immune cells to kill the pathogen. It is like going to war and before the fight begins the battalion has a person to hold a flag to signal the direction of the enemy's approach. 

Here is where I introduce another cell called "CD8 killer cell". CD8 killer cells are also another type of Lymphocyte that are used to kill the invading infection (pathogen). Therefore you will need the CD4 cell and the CD8 cells to evoke an immune response. 

When the body is invaded by a pathogen, the CD4 cells start to identify the pathogen and signal to the CD8 killer cells. CD8 killer cells kill the pathogen after receiving directives from CD4-helper cells. 

How does CD4 count correlate with HIV?

CD4 cells can be reduced in the case of HIV infection. HIV has GP120 on the surface of the virus and it attaches itself to the CD4 receptor on the CD4 cell. Then the HIV virus transfers its genetic material into the CD4 cell and the HIV virus genetic material starts to make copies of itself until the CD4 cell has no more space to contain the HIV replicas inside of the CD4 cell. This causes the CD4 cell to burst and die while liberating more HIV replicas. 

Take a look at this short video for educational purposes here.

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When should I test for CD4?

CD4 count should be tested in cases of suspected immune deficiency syndrome:

  1. HIV (commonly)

  2. Primary immune deficiency (Di George Syndrome)

  3. Lymphoma

  4. Organ transplant

  5. Suspicious persistent recurrent infections without cause

How often should I monitor CD4?

Generally, CD4 count should be monitored as early as 1 month to 3 months. Some very stable cases can be monitored up to 6 monthly. 

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What is the cause of CD4 dropping?

CD4 cell may be a result of HIV disease progression or ineffective HIV treatment.