I totally agree that this kind of research needs to be gone into with eyes wide open (all three of them.)

Main problem that I could see is a goosed-up immune system could easily activate certain auto-immune problems, like arthritis or MS.

Still, if we paralyze lines of research out of what might happen, nothing will ever get done.

The catch to any kind of medical research is that there is no possible way to avoid all risk. Problems can show up even years later, and bingo, the liability lawyers are on you like piranhas.

Tort law is totally out of control, and medical companies and the FDA have had to respond by creating controls so tight on drug development that almost nothing can be developed in a reasonable time, or for anything approaching a reasonable amount of money. Lives are lost from delays too, not just bad drugs.

How much risk is reasonable? Like the homeland security question of how much physical risk we are willing to take to preserve our privacy and other freedoms, it's not an easy question.