IGHE and bronchitis: Causal factors and mechanisms may in some cases be specific farm allergens and IgE-mediated type I sensitization—to e.g. storage mite, bovine or horse allergens –, but the large majority of work-related respiratory symptoms in livestock farmers is caused by innate immunity responses to microbial agents like bacterial endotoxins, glucans and other innate immunity stimulating agents, thus leading to ‘non-allergic asthma’ and bronchitis.