and originally (CC licensed, and attributed) with a few nice illustrations from http://mosaicscience.com/story/why-do-we-have-allergies http://mosaicscience.com

and originally (CC licensed, and attributed) with a few nice illustrations from http://mosaicscience.com/story/why-do-we-have-allergies http://mosaicscience.com/story/why-do-we-have-allergies where they even credit a `Fact checker`. And on first glance, that website seems quite good.