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How does HIV damage the body's ability to use lymphocytes to fight infection?
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blood disease
Peripheral blood smear revealing histopathologic features indicative of a blast crisis in a case of chronic myelogenous leukemia (CML). Blast crisis occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML is characterized by fever, weakness, and an enlarged spleen.
HIV damages the body's ability to fight infection by specifically targeting and depleting helper T lymphocytes (also known as CD4+ T cells), which are essential white blood cells that coordinate the immune response.12
These cells act as the "command center" of the immune system; they produce factors that activate other critical immune cells, including B lymphocytes (which produce antibodies), cytotoxic T lymphocytes (which destroy infected cells), and macrophages (which attack pathogens).1
The virus compromises this system through the following process:
- Infection and Replication: HIV uses its surface protein, gp120, to bind to the CD4 molecule on the surface of helper T cells, allowing the virus to enter and integrate its genetic material into the host cell's genome.12
- Cell Destruction: Once infected, the host cell is used to produce new viral particles, which then bud from the cell surface. Most infected cells die quickly, and the rate of cell loss eventually exceeds the body's ability to produce new helper T cells.12
- Immune Collapse: As the count of helper T cells declines, the immune system loses its ability to activate other defense mechanisms, leaving the body vulnerable to opportunistic infections and cancers.132