Why are diseases of the immune system especially dangerous?

Diseases of the immune system are especially dangerous because they attack the very cells that destroy other diseases. AIDS (auto immunodeficiency syndrome) basically makes the immune system kill itself. Basically, white blood cells kill other cells, (including its own white blood cells) instead of killing viruses or bacteria, in turn making your immune system very weak. If your immune system is weak, a simple cold can turn into a nightmare, and can even result in death.