IGHA1 and Allergy: The major differences between IgA1 and IgA2 lies in the presence of the drastically extended hinge region of IgA1, thought to improve antigen recognition by increasing affinity with antigen epitopes that are spatially distant, but making it vulnerable to proteases.37, 38, 39 The IgE antibody has received an increasing amount of attention because of its role in hypersensivity responses and allergy in the developed world, although initially thought to have evolved to target parasites (eg, helminths and parasitic arthropods) that are too large to be phagocytosed.40, 41, 42