21.   But that seemed like an impossible dream, because HIV attacks the very immune cells the body would use to control the infection.

22.   Capillaries in the brain have specialized cell walls that prevent immune cells and molecules from entering and provoking a harmful immune response.

23.   Cheekbones vanish into cheeks, lost pounds redeposit themselves, lost immune cells return, life plans rewind to the beginning.

24.   Current drugs block one of two enzymes that are used by the virus, HIV, to replicate after it has infected the immune cells.

25.   Eventually, the infected immune cells die off, researchers believe, but no one is sure exactly how long it takes.

26.   Emanuele was part of a research team that first discovered GnRH in immune cells of rats and humans.

27.   Exercise, he added, increases the circulation of immune cells and thus makes the body better able to watch out for bacteria and viruses.

28.   Extremely low immune cell counts leave a patient vulnerable to opportunistic infections such as pneumonia, which often can lead to death.

29.   For example, one criterion might be that a certain percentage of volunteers in study develop certain types of antibodies or specialized immune cells.

30.   For some reason the immune cells botch their central mission, which is to distinguish self from non-self.