How does your immune system work?

Your immune system is made up of a special group of white blood cells called lymphocytes. Some of these lymphocytes, or T cells, are a family of cells and CD4 cells are members of that family. Your immune system has a specific job. It kills the viruses and other germs that get into your body before those viruses make you sick.

Your immune system works all over your body, lymph nodes and white blood cells. Some other examples of how your body's defense system works are:

• skin: keeps all kinds of germs out of your body
• saliva: has things called enzymes in it that can kill germs
• nose: the hair and snot inside your nose clean the air you breathe and keep germs from getting in your body
• vagina, penis, butt hole and bowels (an organ inside your butt where you store poo): have liquid-like stuff in them, called mucous, that helps protect your body