Immunobiology of the graft-versus-host reaction. I. Symptoms of graft-versus-host disease in mice are preceded by delayed-type hypersensitivity to host histocompatibility antigens.

During initiation of an acute graft-versus-host reaction by injection of C57BL/Rij spleen cells into lethally irradiated (C57BL/Rij X CBA/Rij)F1 hybrid mice, a state of delayed-type hypersensitivity (DTH) against host histocompatibility (H) antigens occurs. This was demonstrated by means of transfer of host spleen and lymph node cells into C57BL/Rij recipients, which received a challenge with CBA/Rij spleen cells. Initiation and transfer of the graft-versus-host-related DTH reactivity was highly dependent on Thy-1.2+ cells. The development of DTH reactivity started between 8 and 24 hr after semiallogeneic spleen cell transplantation and increased during the days thereafter. In the spleen maximal DTH reactivity was found on day 4, whereas in the lymph nodes maximal reactivity occurred on day 5 after irradiation and reconstitution. Thereafter, the reactivity decreased until there was no further DTH reactivity demonstrable on day 13. The specificity of the DTH reactivity for host H antigens was proved by no reactivity to a challenge of DBA/2 and Swiss spleen cells, which are H-2-incompatible with CBA cells.