Helminth therapy AKA 'hook worm' therapy involves controlled infestation of a patient with parasitic worms, who produce enzymes which dampen down over active auto-immune response.
The last I heard was this was stuck in clinical trials, so big pharma can produce a drug version, when the worms themselves will clearly suffice. I think it is illegal in the US / UK, but legal elsewhere.
Anyone have any knowledge or updates on this?