Immunotherapy. Can be use for autoimmune conditions and hypogammaglonulinemia.
The beauty of... immunotherapy is that you can structurally design a molecule to specifically target the "enemy" component of a disease, in order to redirect & harness your own body's protective mechanisms to attack & destroy it. Alternatively, you can flood your system with protein complexes that will bind up a harmful molecule in a lock & key manner & neutralize it. Very open-ended answer given huge potential. .