CONTACT HYPERSENSITIVITY IS SUPPRESSED AFTER SENSITIZATION BY DINITROFLUOROBENZENE OF EARLY-STAGE ISO-SKIN GRAFTS

Isologous free skin grafts were applied to the backs of BALB/c mice an d contact hypersensitivity studied by epicutaneous application of DNFB (2,4-dinitro-1-fluorobenzene) to the grafted skin. In the first exper iment, the grafted skin was sensitised and the elicitation reaction as sessed by measuring the ear swelling after five days. Sensitisation wa s not successful until two weeks after grafting. In such non-respondin g animals, re-sensitisation with DNFB on the ungrafted skin area was a lso unsuccessful, indicating the establishment of immunological tolera nce. This tolerance was considered antigen-specific, as re-sensitisati on with oxazolone was successful. In the second experiment, spleen cel l suspension, both untreated and treated in vitro with antiThy 1.2, an tiLyt 1.2, and antiLyt 2.2 antibody, from non-DNFB-responding mice was transferred into normal mice. Subsequently these mice were sensitised with DNFB. Sensitisation was not successful in the untreated group or in those treated with antiLyt 1.2 antibody. On the other hand, the gr oups treated with antiThy 1.2 and antiLyt 2.2 antibody did become sens itised. These results indicate that the unsuccessful delayed hypersens itivity of the grafted skin was caused by suppressor T cells. In addit ion, the density of epidermal Langerhans cells was reduced in the earl y stages of skin grafting and morphological abnormalities were present . From these results, we conclude that contact sensitisation during th e early stage of grafting skin not only produces suppression of ear sw elling but also induces antigen-specific tolerance. These results also suggest that the suppression depends on the antigen-specific suppress or cells and that acquirement associated with a reduction in epidermal Langerhans cells in the grafted skin and abnormalities in their struc ture.