Comparison of alloimmunogenicity of Langerhans cells and keratinocytes from mouse epidermis

Among lymphoreticular cells, Langerhans cells and splenic dendritic cells stand alone in their capacity, when hapten-derivatized, to induce vigorous immune responses, irrespective of route of inoculation, including intravenous. We have examined the comparative efficiency of relatively purified populations of Langerhans cells and their epidermal companions, keratinocytes, to induce alloimmunity when injected intravenously into adult mice. It was found that as few as 100 BALB/c Langerhans cells injected intravenously into C3H mice are capable of inducing specific sensitization as evidenced by subsequent accelerated rejection of BALB/c skin grafts. By contrast, 10,000 BALB/c keratinocytes failed to immunize similarly injected C3H recipients. These results emphasize the unparalleled capacity of Langerhans cells to induce sensitization, and they point to Langerhans cells, among cells within the epidermal compartment, as dominant in the alloimmunogenic potential of skin grafts.