Answer: Your white blood cells aim to destroy the unwelcome guests.
They get their start in your bone marrow. They have a short life -- ranging from a few days to a few weeks -- so your body constantly makes more. There are different types, and they all have the same goal: to fight infection.
They wait, poised for duty, in many different places in your body, including your:
Thymus
Spleen
Tonsils
Blood vessels
Lymph nodes
Small intestine
Adenoids
Lymph Lends a Big Hand
Your lymphatic system is like an inner highway that carries white blood cells through your body.
When you’re sick, you might notice your lymph nodes -- small glands in your neck, groin, armpits, and behind your knees -- are swollen. This is normal. It means your immune system has kicked into high gear to get rid of infection.
Lymph nodes are also filters for your immune system. They catch germs and dead or damaged cells and destroy them.
Hope this helps :)