A few years ago, we had a couple that stayed with us for Shabbat that got cured of Crohns.
The woman had leukemia a few years prior and had a transplant of an immune system. The doctors used chemo (or something like that) to destroy her immune system. The found a perfect match, and took the T-cells from the match and injected her with them. The new T-cells made themselves at home. The lady got a new immune system. She had Crohn’s before the transplant, but it went away after. She got hay fever alergies after.