Migration of rat skin dendritic cells.

This study examines the in vivo migration of rat skin dendritic cells (including Langerhans cells) after skin transplantation. As donor animals, PVG-RT7b rats were used. The leukocytes of these rats bear an epitope of the leukocyte common antigen that can be recognized by use of the antibody His 41. The cells of allogeneic (ACI) recipient strains do not label with this antibody. Four days after transplantation of PVG-RT7b skin on allogeneic recipients, His 41+ cells showing a dendritic morphology were present in the T cell area of the draining lymph nodes. During culture of rat skin explants, dendritic cells migrated spontaneously into the medium. These in vitro migrated cells showed a high capacity to stimulate allogeneic T cells. When these cells, obtained from PVG-RT7b skin, were injected into the hind footpads of allogeneic recipients, they migrated to the same compartments of the draining lymph node. These data indicate that the cells that migrate from a transplanted allogeneic skin grafts are the same cells that migrate in vitro from explants. Most probably, they initiate graft rejection in the draining lymph nodes of the recipient.