Your immune system is your body’s protection against disease. HIV damages immune cells called CD4 cells. If HIV is not treated, your immune system is weakened. A weak immune system can’t fight off infections and you will become ill.
The immune system is the body’s mechanism for protecting itself against the many harmful organisms which try to invade it, such as bacteria and viruses.
It's a highly complex network of tissues, organs and cells, including blood cells.
When an organism gets inside your body (for example, when you breathe in the common cold virus), white blood cells that form part of your immune system go to investigate.
These white blood cells have different roles and work together. One group - the T-cells - co-ordinate the immune response, and other group - the B cells - produce antibodies to fight the problem.
Some T-cells have a protein on their surface called CD4 which is why we often refer to these as CD4 cells.
HIV is dangerous because the virus destroys the very cells of your immune system that are supposed to be keeping you well: the CD4 cells.
HIV attaches itself to a CD4 cell and enters it. Then it makes copies of itself inside the CD4 cell and goes on to damage and destroy the cell. New copies of HIV burst out of the CD4 cell and go off to find more cells to invade.
If the number of CD4 cells (the CD4 count) is reduced, the immune system has fewer cells to help it defend the body from other organisms. This means you're at a greater risk of getting ill.
The immune system does try to fight HIV infection: it produces antibodies that try to fight off the antigens which are a part of the invading organism – in this case HIV. The body will try to mount an attack but for various reasons in the case of HIV it’s unable to eradicate the virus.
Normally the body's immune system would fight off an infection, but HIV prevents it from working properly.
However, effective HIV medication can keep the virus under control, stop you passing on the virus and enable you to live a normal lifespan.
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This article was last reviewed on
by Anna Peters
Date due for the next review: 14/6/2020
Content Author: S. Corkery (NAM)
Current Owner: Kerri Virani
National Institute of Allergy and Infectious Diseases, HIV/AIDS
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