I'll take this one step further to add that Cause does not define Effect, it just explains why Effect took place. One must still account for (and define) the Cause. I won't attempt to guess the cause of each and every autoimmune case, but I will say that in every single one of them the body's immune system is pushed into hyperdrive and turns on itself (inflammation, antihistamine response, etc). That is the definition I'm presenting and I'm sticking with it. As an example: a dog can get frenzied and end up biting it's own tail. The dog is our body. His frenzy is our immune system. His tail is the part of the body the immune system is attacking. Now let me see, what's still missing?... Oh, I know! It's the Cause! The cause is still an unknown factor.
I think the question you really meant to ask was "What CAUSES our body to jump into overdrive?" Does that make sense?