I just spent ages doing a post and Modo deleted it
Billy my Maine Coone suffers badly with Gingivitus, his gums are always bright red and look extremely sore
He's been tested for Calichi and FIV/FeLV but all came back clear. One of my vets did suggest an Interferon mouthwash but I did hear a couple of negative things about this so decided against it. When his starts playing up, he usually has a steroid jab and antibiotics.....usually a course of Baytril which he hates with a vengeance
I think it will get to the stage where he will need to have his teeth removed but will have to have a word with Sean when he next goes in.
I think the fact your friends cat has had the teeth removed, it does sound like an immune system problem but I don't really know much about it. I'm wondering whether the treatment the vet is going to try on Kara for her allergies would work the same on cats with an immune problem......apparently whatever it is, I'm pretty sure the vet said that it boosts the immune system up but not sure if the treatment can only be used on dogs but will find out.