This is such a delightful story about how William Coley came to harness the immune system in the fight against cancer in the 19th century that I just had to share it. Coley used what was basically a bacterial vaccine to treat inoperable sarcomas. His results were quite astounding.
It's also a classic illustration of the hostility the medical establishment can have against new ideas, before realising that the individual is on to something!
If you prefer, there is an option to listen to the story.
I think you'll find it interesting and it may help you to understand the immune system and it's role a little better.