723:
Epicutaneous immunotherapy with peanut directly targets Langerhans cells in human skin
Monday, March 5, 2018
South Hall A2 (Convention Center)
Vincent Dioszeghy, PhD, Emeline Pages, Christophe Dupont, MD, PhD, Hugh A. Sampson, MD FAAAAI, Pascal Descargues, PhD, Lucie Mondoulet, PhD
RATIONALE: Allergen applied on intact skin during epicutaneous immunotherapy is mainly taken-up by Langerhans cells (LCs) and transported to regional lymph nodes, explaining in part the induction of tolerance in allergen-sensitized mice. This study aimed to characterize allergen uptake after epicutaneous administration in an ex vivo human intact skin model.

METHODS:

NativeSkin models consist of ex vivo human skin collected after plastic surgery, which maintain viability for 7 days. Patches loaded with fluorescein-tagged peanut protein extract or PBS were applied to freshly harvested skin inserts from 2 donors for 12 and 24 hrs. Co-localization of PPE-AF647 and LCs (stained with anti-CD207 and anti-CD1a) was evaluated on skin cross-sections by classical fluorescent microscopy and in situ on epidermal sheet layers by confocal microscopy.

RESULTS:

Peanut protein loaded on epicutaneous patches solubilized within 12 hrs due to transepidermal water loss and reached the epidermis. After 24 hrs, a significant increase of PPE-AF647 was co-localized with LCs. For donor#1, 8% of the LCs were co-localized with PPE-AF647, while for Donor#2, 22% of cells were positive. Observation of LCs in contact with PPE-AF647 suggest that there are 2 phases in the process: at 12 hrs, the allergen associates with the surface membrane and at 24 hrs it is internalized in LCs. Other analyses are under investigations (i.e. mRNA expression of cytokines in the tissue).

CONCLUSIONS:

The role of LCs in the antigen uptake and processing following epicutaneous application was confirmed on ex vivo human skin model.