Human papilloma virus (HPV) infection of keratinocytes causes cutaneous warts. Warts induce significant morbidity and disability but most therapies, including cryotherapy, laser and radiofrequency devices show low efficacy. Microwaves induce heating of tissue in a highly controllable, uniform manner and we set out to explore their use in treatment of HPV. We present a pilot study of microwave therapy to the skin in 32 individuals with 52 recalcitrant plantar warts. Additionally, we undertook a molecular characterisation of the effects of microwaves on the skin. Microwave therapy was well tolerated and 75.9% of lesions cleared, which compares favourably to 23-33% success for cryotherapy or salicylic acid. Microwaves specifically induced dendritic cell cross-presentation of HPV antigen to CD8+ T-cells in skin and we show that IL-6 may be important for IRF1 and IRF4 modulation to enhance this process. Keratinocyte-skin dendritic cell cross-talk is integral to host defence against HPV infections, and this study shows that microwave induces anti-HPV immunity which is important for treatment of warts and potentially HPV-related cancers.

Ivan Bristow BSc PhD; Wen Chean Lim BSc PhD; Alvin Lee MBBS (MD); Daniel Holbrook BSc; Natalia Savelyeva PhD; Peter Thomson BSc; Christopher Webb BSc; Marta Polak MSc PhD; Michael R. Ardern-Jones DPhil FRCP (MD PhD)

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