I was just making a general point, that this particular example highlighted - that there are other things to think about. I know some antibodies, that you'd expect to be detected by 'enzymes' (the cited anti-E, for example), may not react as you'd like, but they're not common enough to make us doubt our 'enzyme' panels, I hope (which is why they get published, I guess - who wants to read about ant-E that was detected by 'enzymes'!). Hooves and zebras, as is oft quoted here...