HIV Affects the Immune System
HIV infection is characterized
by a gradual loss of immune function. Specifically, crucial immune
cells, called CD4+T cells, are disabled and killed during the typical
course of HIV infection. These cells, also known as T helper cells, play
a central role in the bodys immune response; they signal other cells in
the immune system to perform special functions. A healthy, uninfected individual
has approximately 1000 CD4+T cells per cubic millimetre (µL) of blood.
When HIV enters a persons
CD4+T cells, it uses the cells to replicate or make copies of itself.
This process destroys the CD4+T cells and the CD4+T "count"
goes down. As CD4+T cells are destroyed, the persons immune system
the course of HIV infection, CD4+T cells are disabled and killed.
When the CD4+ T cell
count falls below 200/µL, the person becomes vulnerable to infections known
"opportunistic infections" and cancers that typify AIDS.
- An opportunistic infection
is an infection that is highly unusual in a person who has a healthy immune
system and is not HIV positive. People with AIDS are frequently affected by
opportunistic infections that attack the respiratory tract, gastrointestinal
tract, neurological system, and other organs, and cancers such as Kaposis
sarcoma and some types of lymphomas.