IGHE and allergic disease: Allergy can be divided into "immunoglobulin E (IgE)-mediated allergy" and "non-IgE-mediated allergy." Non-IgE-mediated allergic reactions can be mediated via, for example, IgG antibodies, T cells, and even by complement activation, that is, by Gell and Coombs type II, III and IV mechanisms (Figure 1) [9,10,35].