Long-term remission of recurrent herpes labialis following topical imiquimod application on distant healthy skin: a clinical and immunological study.

BACKGROUND Given the limitations of current antiviral therapies, safer and more effective approaches to the management of recurrent herpes labialis (RHL) are needed. METHODS A patient with a 23-year history of RHL and 14 healthy individuals were studied. The patient applied imiquimod to distant healthy skin for 3 weeks. Peripheral blood (PB) samples were collected from the patient during treatment and 21 months after its discontinuation; samples were collected from the controls once. The distribution of lymphocyte populations in PB were analysed by flow cytometry and PB cytokine levels were measured using cytometric bead arrays. RESULTS The patient showed long-term remission of the disorder subsequent to a 3-week imiquimod application to distant healthy skin. Imiquimod treatment induced the activation and proliferation of T-helper and cytotoxic T-cells, B-cells and T-regulatory cells. In addition, there was a very strong transient increase of T-helper 1 cells (resulting in interferon-γ secretion) and type 1 (pro-inflammatory) polarization of the immune response accompanied by a sustainable interferon-α production. At follow-up 21 months after treatment cessation, with the patient remaining relapse-free, the patient had control levels of all cytokines, increased levels of activated cytotoxic T-cells, continuous production of new T-helper cells and B-cells and near-to-normal levels of T-regulatory cells. CONCLUSIONS Our results indicate that topical application of imiquimod to healthy skin is capable of causing systemic immunomodulation. This treatment might represent a new and effective alternative to established therapeutic and prophylactic regimens for RHL.