> Imagine a billion nanobots swarming inside your body, networked [1] and analyzing every cell they come across. Over time, they build a gigantic database of yo

> Imagine a billion nanobots swarming inside your body, networked [1] and analyzing every cell they come across. Over time, they build a gigantic database of your cells. Then they'll be able to use some heuristics to determine whether any given cell is a menace to your health. You've basically described the immune system! The immune system is imperfect, but it's a lot more complicated than any man-made system so far. Trillions of cells, thousands of genes controlling each one, hypermutations creating billions of different antibodies, slipping into and out of each corner of the body. Basically, organized chaos; by some measures, more complicated than the brain. I would welcome potential designs for an auxiliary system, but what we have already is hard to understand, much less supplant. Certainly the concept of retraining the immune system is appealing, and looking beyond the OP's microbead/reinfusion rigamarole, we've already been doing that for decades via vaccines.