A small number of people never become infected with HIV despite years
of exposure to the virus. For example, they may have repeated, unprotected sex
with an infected person. These people are said to be HIV-resistant.
CD4 cells are a type of white blood cell that fights infection. Another name for them is T-helper cells. CD4 cells are made in the spleen, lymph nodes, and thymus gland, which are part of the lymph or infection-fighting system. CD4 cells move throughout your body, helping to identify and destroy germs such as bacteria and viruses.
The CD4 count measures the number of CD4 cells in a sample of your blood drawn by a needle from a vein in your arm. Along with other tests, the CD4 count helps tell how...