IGHE and allergic disease: To further account for known regulatory differences of different allergy types, we stratified participants according to either the presence of contact allergy as the most prevalent T cell-mediated type IV allergy or hay fever as the most prevalent IgE-mediated type I allergy (also see Section 2.1) resulting in an extracted subpopulation of 770 subjects equally distributed into allergy cases and healthy, allergy-free control subjects.