Promiscuous recognition of major histocompatibility complex class II determinants in cyclosporine-induced syngeneic graft-versus-host disease: specificity of cytolytic effector T cells.

BACKGROUND: Administration of the immunosuppressive drug cyclosporine after syngeneic/autologous bone marrow transplantation paradoxically elicits a systemic autoimmune syndrome resembling graft-versus-host disease (GVHD). This syndrome, termed autologous or syngeneic GVHD, is associated with the development of a highly restricted repertoire of cytolytic T lymphocytes that promiscuously recognizes major histocompatibility complex class II determinants, including self.
METHODS: Vbeta8.5+CD8+ effector lymphocytes and T-cell clones were isolated from Lewis rats with cylosporine-induced syngeneic GVHD. The specificity of the effector T cells and T-cell clones was examined in vitro. The pathogenicity of the T-cell clones was confirmed in vivo using a local graft-versus-host reaction assay.
RESULTS: Clonal analysis reveals that the pathogenic effector T cells recognize a peptide from the invariant chain termed CLIP in association with major histocompatibility complex class II determinants. Moreover, there appears to be an additional interaction between the N-terminal flanking region of CLIP and the Vbeta segment of the T cell receptor.
CONCLUSION: The results suggest that recognition of this highly conserved peptide along with the additional interaction between the flanking region and the T cell receptor may account for the promiscuous activity of the autologous/syngeneic GVHD autoreactive T cells.