I was dx'd with Fibromyalgia/CFS 20 years ago. My family all has Ankylosing Spondylitis, tho I don't present the HLA-B27 antibodies, so I didn't get that dx, thankfully! Needless to say, these past 20 years have been hell!
Until the PB, that is. It works for me, and I have been symptom free for months! Not only have I been able to get out of a nasty flare (post cancer-treatment), but I've been able to do things that would always, in the past, have put me into flare. I haven't had a brain-fog in over 6 months. That blows my mind.
I'm not 100% Primal, but I am better than 80%. I find that it's a matter of management. The closer I stick to the PB, the better I feel. The further I slip, the less good I feel. Sometimes, I notice that I've slipped a little too far, and have started to feel just a little tired or blue - and then I know it's time for a fast and lots of rest, and I'll be back in the game in no time. This is NOT how it used to be, on the standard American diet, let me tell you!
I do want to mention, that in my experience, it's not simply the diet. It's about the physical aspect, too. The daily moving around makes a big difference. Initially, I relied on dietary changes to get me back on my feet and able to get out of bed again. Once I was able to move around on a daily (or most-daily) basis, is when I started to see the real change, tho. My rule: NEVER over-do it. Those who are otherwise healthy are much more able to recover than those of us with FMS/CFS/etc. It simply takes us longer.
So here's another voice for the success of the PB in dealing with autoimmune issues!!!