Abstract
Plasmacytoid dendritic cells (pDCs) constitute a subset of dendritic cells known to be the “professional” interferon type I (IFN-I) producers. pDCs play an important role in antiviral immunity, as well as linking innate and adaptive immunity. Under normal conditions pDCs are not present in skin. They are shown to be a part of the inflammatory infiltrate in different skin conditions including erythema multiforme (EM). This condition is considered to be a cell-mediated immune reaction to a wide variety of agents, most commonly herpes simplex virus. Nevertheless, the pathophysiology of EM still remains unclear. In this study, we grouped 32 biopsies from 30 patients diagnosed with EM, based on their etiology and analyzed the density and distribution of CD123 positive pDCs. In all cases we observed a greatly increased number of pDCs in the dermal inflammatory infiltrate. Virally-induced EM (by herpes simplex virus (HSV) and other viruses) was more likely to have a significantly higher number of pDCs compared to non-virally associated EM. Hence, we think that pDCs play a key role in the pathogenesis of EM independent of etiology and may play an increased role in virally-associated cases. Further studies on pDCs would clarify their importance in EM and improve our understanding of the pathophysiology of this disease.
Highlights
Plasmacytoid dendritic cells are a unique subset of conventional dendritic cells [1,2,3]
DNA via the Toll-like receptor [1,2,3]. Under normal conditions they are not present in the skin, but upon cutaneous injury Plasmacytoid dendritic cells (pDCs) migrate from the peripheral blood into the affected area [2,3]. They subsequently respond to stimuli through Toll-like receptors 7 and 9 (TLR7 and TLR9) by releasing high quantities of type I interferon, IFN-α, contributing to ongoing inflammatory invents [2,3]. pDCs play a specialized role in antiviral immunity as well as systemic autoimmunity [4]
We grouped the cases according to the etiologic category and percentage of the pDCs in the dermal inflammatory infiltrate
Summary
Plasmacytoid dendritic cells (pDCs) are a unique subset of conventional dendritic cells [1,2,3]. DNA via the Toll-like receptor [1,2,3] Under normal conditions they are not present in the skin, but upon cutaneous injury pDCs migrate from the peripheral blood into the affected area [2,3]. They subsequently respond to stimuli through Toll-like receptors 7 and 9 (TLR7 and TLR9) by releasing high quantities of type I interferon, IFN-α, contributing to ongoing inflammatory invents [2,3]. It is sensible that pDCs might be involved in pathology of erythema multiforme (EM), there is only scattered information about their role in this skin condition [5]
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