Concerning Immune System Responses and Gene Mods
Natural Proteins that act as Immune-suppressants: TGF-beta, Neurokinin B --> (which produces Phosphocholine), MHC (HLA-E/G). They don't suppress the entire immune system, they just protect the cell that is producing that protein from getting attacked by your body.
Because these are proteins, they can be encoded for via genes. I guess you guys can see where I am going with this. Anyway, cheers