Plasmacytoid dendritic cells and type I interferon in the immunological response against warts

Abstract

Background: Plasmacytoid dendritic cells (pDCs) are the most potent producers of type I interferons (IFNs), and are involved in the pathogenesis of several cutaneous infectious (especially viral), inflammatory/autoimmune and neoplastic entities. Their role in the pathogenesis and regression of human papilloma virus (HPV)-induced skin lesions has not been well studied. Aim: To investigate pDC occurrence and activity in HPV-induced skin lesions, including inflamed and uninflamed warts as well as epidermodysplasia verruciformis (EDV)-associated lesions. Methods: In total 20 inflamed and 20 uninflamed HPV-induced skin lesions (including 7 EDV lesions) were retrieved from our database, and the tissue was immunohistochemically tested for pDC occurrence and activity using anti-BDCA-2 and anti-MxA antibodies, respectively. Results: pDCs were present in all 20 inflamed warts and absent from all 20 uninflamed cases. MxA expression was also diffuse and strong in 75% (15/20) inflamed warts, but not in any of the uninflamed warts. Conclusions: pDCs constitute a central component of the inflammatory host response in inflamed warts, possibly contributing to their regression through production of type I interferons. © 2017 British Association of Dermatologists