I did a thought experiment about how the immune system must work and came up with a simple system using only mechanisms that I know are available molecularly.

I did a thought experiment about how the immune system must work and came up with a simple system using only mechanisms that I know are available molecularly. If you could have a bunch of random protein sensors that undergo a training phase where they learn what "Host" is. Anything that makes a "detection" during training is discarded. Anything that doesn't is either never going to detect stuff, or might detect something "Foreign". These then float around your blood stream and either do nothing until they are lost, or go crazy replicating and raising the alarm when something Foreign shows up. A danger with this method is random sequences that are just really bad at detecting "Host" or a training period that is cut short. This might lead to autoimmune responses. This thought might give some hints about how to combat autoimmune diseases without disrupting the greater immune system.