Couldn't you tell this apart by the kind of damage caused to one's own cells and what kind of antibodies are present? e.g. https://en.wikipedia.org/wiki/Antinuclear_antibody
I jest but I think these tests are still a bit of a mystery (as in why these autoantibodies are made and what their significance is) especially as some people with high titres have no symptoms and vice versa although there is an association.
I think what parent is alluding to is that the trigger for production may be an infection, even if the damage is mediated by one’s own immune system.
[0]for a chuckle this is a humorous but accurate depiction: https://twitter.com/DGlaucomflecken/status/13719013464131174...
A pretty big association I thought
Also what is there exactly to interpret? Or what would a good interpretation look like? I've been to a rheumatologist before and they didn't exactly explain.