Figure 4: Contribution of autoreactive IgE to bullous pemphigoid pathophysiology
IgE AAb in bullous pemphigoid are directed to the intracellular hemidesmosome protein BP230 and the transmembrane ECM-linker protein BP180 located in the basement membrane zone (BMZ) of the skin. These auto-IgE have a high prevalence in BP patients and share the same epitopes with co-occurring autoreactive IgG. Crosslinking of FcεRI on mast cells and eosinophils in skin lesions of BP patients has been demonstrated, and anti-IgE therapy with omalizumab has been reported to be beneficial in a small cohort of patients. However, no consistent relationship between IgE AAb levels and disease activity in BP patients has been established yet. Increased expression of cell-bound and soluble IgE receptors in BP including sFcεRI and sCD23 further suggests a complex regulatory network of IgE production.