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How does HIV damage the immune system?
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AIDS
Scanning electron micrograph of HIV-1 virions (green) budding from a cultured lymphocyte. Multiple round bumps on the cell surface represent sites of virion assembly and budding.
HIV damages the immune system primarily by targeting and destroying helper T cells, also known as CD4+ T cells. These cells are essential to the immune system because they produce factors that activate other immune cells, including B lymphocytes (which produce antibodies) and cytotoxic T lymphocytes (which kill infected cells).12
The virus infects these cells by binding its gp120 protein to the CD4 receptor on the T cell surface, allowing the viral genetic information to enter and hijack the cell's machinery to replicate. This process leads to the following impacts:1
- Cell Death: Most infected helper T cells die quickly. As the rate of cell loss exceeds the body's ability to produce new cells, the overall CD4 count declines.1
- Immune Suppression: With fewer helper T cells available to coordinate the immune response, the body becomes increasingly unable to fight off infections and malignancies.13
- Rapid Mutation: HIV evolves rapidly, allowing it to escape detection by the immune system and develop resistance to treatments.13
When the CD4 count drops significantly, the individual becomes susceptible to opportunistic infections, marking the progression to AIDS.3