@woodsroad No where in that article did it say that you can become immune to an allergy, but of course allergies and immunity are linked. But, you cannot become immune to something that you have an allergy to in the way that you suggest in your post above.
I have been around all sorts of pigweed varieties, also known as amaranth. But in my 50's have become allergic to it.
also, my newly found metal allergies come from being exposed to nickel for so long.
Unlike immunity to germs and diseases, exposer to allergen do not heal an allergy.
They don't work the same way.