Specificity of effector T lymphocytes in autologous graft-versus-host disease: Role of the major histocompatibility complex class II invariant chain peptide

Administration of the immunosuppressive drug cyclosporine after autologous bone marrow transplantation induces a systemic autoimmune syndrome resembling graft-versus-host disease (GVHD). This syndrome termed autologous GVHD has significant antitumor activity. Associated with autologous GVHD is the development of T lymphocytes that recognize major histocompatibility complex (MHC) class II determinants, including self. The present studies attempted to characterize and define the molecular specificity of the effector T lymphocytes in autologous GVHD induced in patients with metastatic breast cancer. The results suggest that the effector cells associated with human autologous GVHD are CD8(+) T lymphocytes expressing the alpha/beta T-cell receptor, Additional studies show that the effector T cells recognize MHC class II antigens in association with a peptide from the invariant chain (CLIP). Pretreatment of autologous lymphoblast target cells with anti-CLIP antibody completely blocked lysis mediated by autologous GVHD effector T cells, On the other hand, force loading this peptide markedly enhanced the susceptibility of the target cells to recognition by the autoreactive T cells. The recognition of the MHC class II CLIP complex may account for the novel specificity of the effector T cells associated with human autologous GVHD, Moreover, identification of the target peptide may allow for the development of novel immunotherapeutic strategies to enhance the antitumor efficacy of autologous GVHD. (C) 1997 by The American Society of Hematology.