What it means
CD4 marks the helper T cells that direct much of the immune response. HIVaych-eye-VEE (said as letters)Human immunodeficiency virus: a virus that infects and destroys immune cells called CD4 T cells.Full entry infects and destroys these cells, so the CD4 count shows how strong the immune system is in a person with HIV. A normal count is roughly 500 to 1,500 cells/mm³. A count below 200 cells/mm³ is one way AIDSAYDZAcquired immunodeficiency syndrome: the most advanced stage of HIV infection, when the immune system is badly damaged.Full entry is defined and brings a high risk of serious infections.
At a glance
| Also written | CD4 cell, CD4 cells |
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Related terms
immune system
The body's defense system of cells, tissues and organs that fights germs and other foreign substances.
HIV
Human immunodeficiency virus: a virus that infects and destroys immune cells called CD4 T cells.
AIDS
Acquired immunodeficiency syndrome: the most advanced stage of HIV infection, when the immune system is badly damaged.
CD4 count
A blood test that counts CD4 T cells, the white blood cells that HIV infects and destroys.