Perhaps a potential treatment would be a drug which made the older immune system work like it was younger? In some way stimulated it to be so?
Isn't this the way some potential anti-cancer drugs are going now, enable the immune system to detect problems and deal with them early on at a cellular level?
I think you're referring to the tree of life.
I believe once you start messing with nature, you're asking for trouble. If you up-regulate the immune system I would guess other systems of the body would suffer side effects that could be fatal. A bit like putting a more powerful engine into a car and not installing the correct suspension and brakes to match.
As we age we degenerate; that's life! it's all about the ability of our cells and whether they can continue to divide and multiply. That's why exercise and diet play a crucial role in life. use it or lose it and good clean fuel in the system.
If you do have any references to what you said above I'd be interested if you'd post a link.