Déficit immunitaire associé à la réaction expérimentale du greffon contre l'hôte. Absence de corrélation avec l'activité cytotoxique des lymphocytes T.

: Graft-versus-host reactions (GvHR) are initiated by T lymphocytes. In mice, the T cell subset involved depends on the incompatibility for minor or major histocompatibility antigens between donor and host. However, the correlation between phenotype and function is not absolute, and anti-host cytotoxic T cells can be detected in recipients without GvHR. We have presently investigated in a P----F1 model differing at the MHC, whether GvH associated immunosuppression was correlated with donor cytotoxic T cell activity. The immunodeficiency was tested by the ability of the F1 mice to generate a cytotoxic T cell response against TNP self or an alloantigen. F1 specific parental cytotoxic T cells generated in vitro induced less immunosuppression than naive parental spleen cells. Specific in vivo priming increased the cytotoxicity of parental spleen cells, but decreased their capacity to induce GvH associated immunosuppression. In contrast, non specific priming resulted the usual immunodeficiency. Spleens of the F1 mice injected with specific cytotoxic T cells were very enlarged, suggesting that these cells remained capable of inducing a GvHR without generating immunosuppression.