Interleukin‐33 is expressed in the lesional epidermis in herpes virus infection but not in verruca vulgaris

Interleukin (IL)‐33 is released on cell injury and activates the immune reaction. IL‐33 is involved in antiviral reaction in herpes virus infection, but the source that secretes IL‐33 has not been identified. We speculate that keratinocytes injured in herpes virus infection secrete IL‐33. In order to detect IL‐33 in the lesional epidermis of patients with herpes virus infection, we immunostained several cutaneous herpes virus infection samples with an anti‐IL‐33 antibody, and compared them with cutaneous human papilloma virus (HPV) infection samples. We observed strong nuclear and mild cytoplasmic staining in epidermal keratinocytes of the lesional skin samples with herpes simplex virus and varicella zoster virus infections. However, staining was not observed in the epidermis of verruca vulgaris (VV) samples. We assumed that the strong immune reaction to herpes virus infection may depend on strong IL‐33 expression in the epidermis, while very weak immune reaction in samples from patients with VV may be due to low or no expression of IL‐33 in the lesional epidermis.