T-cells are specialized white blood cells that play an important role in the body's immune system.
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There are two primary types of T-cells.
- CD4 Cells - These cells have molecules called CD4 on its surface. These "helper" cells initiate the body's response to invading micro-organisms such as viruses.
- CD8 Cells - These types of T-cells have a molecule called CD8 on their surface. CD8 cells destroy cells that have been infected with foreign invading micro-organisms. CD8 cells also produce antiviral substances (antibodies) that help fight off the foreign invader.
Understanding the Immune Response
CD4 Cells - The Key to HIV Replication
HIV is a retrovirus, meaning it needs cells from a "host" in order to make more copies of itself (replication). In the case of HIV, CD4 cells are the host cells that aid HIV in replication. HIV attaches to the CD4 cells, allowing the virus to enter and infect the CD4 cells, damaging them in the process. The fewer functioning CD4 cells, the weaker the immune system and therefore the more vulnerable a person is to infections and illnesses.
How Do We Know How Many Functioning CD4 Cells There Are?
Knowing how many functioning CD4 cells are circulating in the blood gives the HIV doctor an idea of how strong the HIV+ person's immune system really is. A simple blood test called the CD4 count measures the number of functioning CD4 cells in the body and therefore measures the health of the immune system. The CD4 blood test results can vary a great deal.Normal Values - In a healthy adult, a normal CD4 count can vary a great deal but is typically 600 to 1200 cells per cubic millimter of blood
Between 600 and 350 - In an HIV+ person, this range is considered "very good".
- HIV medications are typically not be indicated.
Between 350 and 200 - The immune system is weakened and therefore the HIV+ person may be at increased risk for infection and illness.
- Your doctor may consider starting HIV medications.
Less that 200 - The immune system is severely weakened and the HIV+ person is at a much greater risk of opportunistic infections.
- HIV medications and prophylactic antibiotics will be prescribed to help prevent illnesses and infections.
