Characterization of Dendritic Cells Subpopulations in Skin and Afferent Lymph in the Swine Model

Transcutaneous delivery of vaccines to specific skin dendritic cells (DC) subsets is foreseen as a promising strategy to induce strong and specific types of immune responses such as tolerance, cytotoxicity or humoral immunity. Because of striking histological similarities between human and pig skin, pig is recognized as the most suitable model to study the cutaneous delivery of medicine. Therefore improving the knowledge on swine skin DC subsets would be highly valuable to the skin vaccine field. In this study, we showed that pig skin DC comprise the classical epidermal langerhans cells (LC) and dermal DC (DDC) that could be divided in 3 subsets according to their phenotypes: (1) the CD163(neg)/CD172a(neg), (2) the CD163(high)CD172a(pos) and (3) the CD163(low)CD172a(pos) DDC. These subtypes have the capacity to migrate from skin to lymph node since we detected them in pseudo-afferent lymph. Extensive phenotyping with a set of markers suggested that the CD163(high) DDC resemble the antibody response-inducing human skin DC/macrophages whereas the CD163(neg)CD172(low) DDC share properties with the CD8(+) T cell response-inducing murine skin CD103(pos) DC. This work, by showing similarities between human, mouse and swine skin DC, establishes pig as a model of choice for the development of transcutaneous immunisation strategies targeting DC.