Characterization and functional analysis of skin-derived dendritic cells from swine without a requirement for in vitro propagation

A low-density cell population was isolated from skin explants of pigs and characterized as a highly enriched dendritic cell (DC) population based on phenotypical and functional properties. The skin-derived DCs were identified by their characteristic ultrastructural properties as well as by consistent co-expression of the CD1 and SWC3a antigens that clearly differentiate them from other porcine leukocytes. These cells exhibit higher expression of porcine MHC class II (SLAII) and CD80/86 antigens as compared to macrophage/monocyte cells. They consistently expressed the S100β antigen at high levels and did not express the lymphoid markers CD3, CD4 or CD8. Within this population of skin-derived DCs there was variable expression of CD11c, CD14 and CD16. Functional characterization of this DC population revealed that they are efficient in uptake and processing of soluble protein antigens and in endocytosis of small (0.02 μm) but not large (2 μm) polystyrene beads. Further, these cells were efficient inducers of primary allogeneic responses and in stimulating antigen-specific and mitogen-induced proliferation and IFNγ responses in autologous lymphocytes. This study provides important information to further characterize the cutaneous DCs and develop models to analyze the role of these cells in immune responses in vivo.