title: Murine gamma/delta-expressing T cells affect alloengraftment via the recognition of nonclassical major histocompatibility complex class Ib antigens.
abstract: T cells with antidonor specificities have been isolated from human recipients experiencing graft rejection after allogeneic bone marrow transplantation (BMT). Partial T-cell depletion of unrelated BM grafts with an anti- T-cell receptor (TCR) monoclonal antibody (MoAb) directed against the TCR alpha/beta heterodimer have shown that the incidence of graft-versus-host disease is low and that the incidence of durable engraftment is high. These studies suggest either that the number of residual TCR alpha/beta+ cells was sufficient to permit alloengraftment or that the preservation of cells other than TCR alpha/beta+ cells was beneficial for engraftment. With respect to the latter, one such candidate cell is the TCR gamma/delta+ T cell. Because no studies have specifically examined whether TCR gamma/delta+ cells might be capable of eliminating BM-derived hematopoietic cells, we established a new graft rejection model system in which transgenic (Tg) H-2d mice (termed G8), known to express gamma/delta heterodimers on high proportion of peripheral T cells, were used as BMT recipients. These Tg TCR gamma/delta+ cells respond vigorously to target cells that express the nonclassical major histocompatibility complex (MHC) class lb region gene products encoded in H-2T region of H-2T(b)+ strains. G8 Tg mice were used as recipients for C57BL/6 (B6: H-2(b); H-2T(b)) T-cell-depleted (TCD) donor BM. We show that G8 Tg (H-2(d), H-2T(d)) mice are potent mediators of B6 BM graft rejection and that the rejection process was inhibited by anti-TCR gamma/delta MoAbs. In contrast, BM from a B6 congenic strain that expresses the H-2T(a) allele, B6.A-Tl(a)/BoyEg, was readily accepted, suggesting that H-2T antigens on repopulating donor BM cells are the targets of host graft rejecting T cells that express the TCR gamma/delta heterodimer. PB chimerism studies were performed at > or = 1.5 months post-BMT using TCD BM from severe combined immunodeficient allogeneic donors, which is highly susceptible to rejection by the host. The addition of donor G8 TCR gamma/delta+ cells to TCD donor BM was shown to significantly increase alloengraftment in B6 recipients. These results show that (1) host TCR gamma/delta+ cells can reject repopulating donor cells, presumably by responding to nonclassical MHC class lb gene products expressed on BM-derived hematopoietic progenitor cells; and (2) donor TCR gamma/delta+ cells can facilitate the alloengraftment of rigorously TCD donor BM.
authors.affiliation: Department of Pediatrics, University of Minnesota Hospital, Minneapolis, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Blazar
authors.forename: P A
authors.initials: PA
authors.lastname: Taylor
authors.forename: J A
authors.initials: JA
authors.lastname: Bluestone
authors.forename: D A
authors.initials: DA
authors.lastname: Vallera
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use; D016026:Bone Marrow Transplantation / Q000276:immunology*; D017252:CD3 Complex / Q000032:analysis; D005260:Female; D005677:G(M1) Ganglioside / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology* / Q000517:prevention & control; D006183:H-2 Antigens / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D008822:Mice, Transgenic; D011828:Radiation Chimera / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis / Q000276:immunology; D016511:Severe Combined Immunodeficiency / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014184:Transplantation, Homologous / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D006183:H-2 Antigens; D015395:Histocompatibility Antigens Class I; D016692:Receptors, Antigen, T-Cell, gamma-delta; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside