Comparison of microneedles and adhesive-tape stripping in skin preparation for epicutaneous allergen delivery

Background: Epicutaneous immunotherapy targets the network of dendritic cells in the epidermis. Allergen exposure of the dermal layers should be limited as these contain mast cells and blood vessels, which increases the risk for local and systemic allergic reactions. Methods: This intraindividually controlled trial included 20 subjects with birch pollen allergy. Three areas of the volar forearms were treated by repeated adhesive-tape stripping, single-prick lancet piercing and microneedle array application. Four 10-fold dilutions of allergen extract were applied to each area and the IgE-mediated immediate-phase reactions and cell-mediated eczema were assessed. Results: Allergen application after tape stripping led to an immediate-phase reaction in 2 subjects (10%) at the highest allergen concentration of 10 HEP/ml. Both prick needle and microneedle pretreatment resulted in immediate-phase reactions in all subjects (100%). The reactivity pattern, however, differed significantly: 95% of the reactions after pricking occurred at concentrations of ≤0.1 HEP/ml, whereas 50% of the reactions after microneedle preparation were noted at ≥1 HEP/ml. In 3 subjects (15%), eczema was observed on the microneedle-treated skin area. No serious adverse events occurred. Conclusions: Microneedles enhance stratum corneum penetration when compared to tape stripping. However, they do not resolve the problem of mast cell-mediated local reactions, possibly due to diffusion into the dermis. The occurrence of eczema after the microneedle treatment suggests induction of dendritic cell-mediated T cell responses. Therefore, skin preparation with microneedles may be a promising method for epicutaneous allergen immunotherapy.