IgE and FcεRI are highly expressed on innate cells in psoriasis

Summary Background Although elevated serum IgE levels have been reported in psoriasis, the role of IgE in psoriasis still needs to be clarified. Objectives To analyse serum total IgE levels in addition to the presence and distribution of IgE and FcεRI in psoriatic lesions, and to investigate alteration of IgE and FcεRI after successful systemic treatment. Methods Total serum IgE levels were determined using enzyme‐linked immunosorbent assay. The expression and localization of IgE and FcεRI was investigated using immunohistochemistry and double immunofluorescence. Results Elevated total serum IgE levels were found in 39% of patients with psoriasis. The levels of total serum IgE were significantly higher in male patients compared with female patients. Furthermore, total serum IgE levels decreased after successful systemic treatment. A positive correlation between IgE+ and FcεRI+ cells and a significant increase of these cells was found in psoriatic lesions when compared with normal skin. Interestingly, IgE+ and FcεRI+ cells decreased significantly after successful therapy with ustekinumab. IgE and FcεRI were coexpressed on mast cells, epidermal Langerhans cells, dermal dendritic cells, macrophages and a small number of neutrophils. Conclusions IgE might participate in the development of psoriasis by activating FcεRI‐bearing cells. What's already known about this topic? Serum total IgE levels are elevated in patients with psoriasis. What does this study add? The expression of IgE and FcεRI was particularly enhanced on innate cells in psoriatic lesions. The numbers of IgE+ and FcεRI+ cells in psoriatic lesions significantly decreased after treatment with ustekinumab. What is the translational message? IgE‐mediated mechanisms may perpetuate cutaneous inflammation in a subset of patients with psoriasis. Linked Comment: Heeringa and van Zelm. Br J Dermatol 2016; 175:16–17 Plain language summary available online