If some part of the innate auto-immune system doesn't react, it could cause POIS type symptoms.
IL-6 for instance is a disinflamatory. In some innate reactions, like exercise, it rises to prevent inflamatio. If it does not rise, you suffer inflamation (I've heard that this permits inflamation of the meningis, 'nervous system covering'), which would produce nervous system pain AND cognitive problems.
In this case, it says that IL-6 does not activate normally, so maybe it's not precisely this.... but some other element, either activating or not activating when it should.....