As a teenager, living in a house kept reasonably clean (as clean as a house with three teenagers and innumerable pets can be), I suffered from asthma, an autoimmune disease.
When I lived alone, most of my life so far, I had no autoimmune disease.
Now I’m living with my partner, who keeps the place clean, I’ve another autoimmune disease.
I am not a tidy person. I don’t see things fussy people consider dirt. If food falls on the floor, I don’t immediately fret. When I was a child, if something vaguely edible fell, it was gone: that’s one of the benefits of living with dogs (I’d have dogs now were my lifestyle suitable).
So, clean and tidy, I get an autoimmune disease. Mucky and yucky, I’m healthy.
Sounds simple, doesn’t it.
Of course, it isn’t simple. My current malady leaves blotches on my legs, with occasional itching, but apart from that I don’t notice it. With these symptoms, when living alone, I probably wouldn’t have noticed it at all. I’d have occasional itchy rashes, and I’d see them as itchy rashes that’d go away (and they went away). My current disease may be an old friend revisiting, not something new.
So it’s quite plausible that my malady now is no more than a flare up of something innocuous and ancient. This time, though, my partner noticed, and got me to go get it doctored.
So, on the surface, the correspondence of the autoimmune diseases and lifestyle suggests that if my immune system has nothing to attack, it has a go at me. But, actually, with a slightly deeper look, no such conclusion is sensible.