I found this. There are a lot of big words in it but it does mention many of the symptoms that you've described. http://maxshouse.com/Diseases_of_the..._foliaceus.htm

Also this. It mentions one of the possible reasons for autoimmune disease in cats, which you also mentioned. http://www.paws-and-effect.com/html/pawsandeffect9.html

I'm sorry that I can't be of more help. I've not experienced this myself w/any of my cats. I do hope that your friend is able to get it under control w/her dear kitty.