I had some difficult symptoms of immune hyperactivation, along with immune suppression (?). I believe I've heard it's an natural killer cell thing many ME/CFS patients have.
My ME/CFS doc prescribed Cortef, which did cut down some on the "reacting to everything". Not a huge improvement, but helpful. When a different ME/CFS doc prescribed Valcyte, he discontinued the Cortef. The hyper-reactivity hasn't returned.
Dunno if that helps any, but that's my experience.