You could try high dose B12. It increases the activity of T suppressor cells which can help to curb immune reaction to foods caused by hyper permeability of the digestive system.
It's not without risks as with any form of immune suppression.
The dosage required is in the order of 20mg to 25mg/day but you might get some effect on a lower dose. If you try then increase and decrease slowly, especially if you decrease it.
It does need to be a usable form of B12 such as methylcobalamin which can be expensive.