IGHE and Autoimmunity: The two distinct autoimmune responses that have been suggested to be relevant in CSU are (1) type I autoimmunity (autoallergy), which entails the occurrence of IgE autoantibodies to self-antigens such as thyroid peroxidase, and (2) type IIb autoimmunity, which entails IgG autoantibodies against the high-affinity IgE receptor, FcεR1, or IgE itself [4] (Figure 1).