Effect of topical vitamin D analogue on in vivo contact sensitization

Background: The immunomodulatory role of vitamin D and its analogues has been demonstrated in vitro and in vivo using animal models. We evaluated the effect of a vitamin D analogue, calcipotriene, in vivo on human subjects using a contact hypersensitivity model. Observations: Subjects were pretreated with topical calcipotriene, simulated solar radiation, or both on buttock skin. They were then sensitized and challenged using the contact allergen dinitrochlorobenzene. Immune response was measured by change in skinfold thickness before vs after elicitation across the challenge sites. Conclusions: Calcipotriene- treated individuals demonstrated 64% immunosuppression compared with untreated controls. This is equivalent to the immunosuppression induced by UV exposure.