title: Islet allograft rejection by contact-dependent CD8+ T cells: perforin and FasL play alternate but obligatory roles.
abstract: Though CD8(+) T lymphocytes are important cellular mediators of islet allograft rejection, their molecular mechanism of rejection remains unidentified. Surprisingly, while it is generally assumed that CD8(+) T cells require classic cytotoxic mechanisms to kill grafts in vivo, neither perforin nor FasL (CD95L) are required for acute islet allograft rejection. Thus, it is unclear whether such contact-dependent cytotoxic pathways play an essential role in islet rejection. Moreover, both perforin and CD95L have been implicated in playing roles in peripheral tolerance, further obscuring the role of these effector pathways in rejection. Therefore, we determined whether perforin and/or FasL (CD95L) were required by donor MHC-restricted ('direct') CD8(+) T cells to reject islet allografts in vivo. Islet allograft rejection by primed, alloreactive CD8(+) T cells was examined independently of other lymphocyte subpopulations via adoptive transfer studies. Individual disruption of T-cell-derived perforin or allograft Fas expression had limited impact on graft rejection. However, simultaneous disruption of both pathways prevented allograft rejection in most recipients despite the chronic persistence of transferred T cells at the graft site. Thus, while there are clearly multiple cellular pathways of allograft rejection, perforin and FasL comprise alternate and necessary routes of acute CD8(+) T-cell-mediated islet allograft rejection.
authors.affiliation: Barbara Davis Center for Childhood Diabetes, University of Colorado Health Sciences Center, Department of Medicine, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sleater
authors.forename: A S
authors.initials: AS
authors.lastname: Diamond
authors.forename: R G
authors.initials: RG
authors.lastname: Gill
mesh_terms: D000208:Acute Disease; D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D002465:Cell Movement; D002478:Cells, Cultured; D004195:Disease Models, Animal; D053222:Fas Ligand Protein / Q000378:metabolism*; D005260:Female; D005805:Genes, MHC Class I / Q000502:physiology; D006084:Graft Rejection / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D007515:Islets of Langerhans / Q000473:pathology; D016381:Islets of Langerhans Transplantation / Q000276:immunology* / Q000473:pathology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins / Q000378:metabolism*; D011379:Prognosis; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D014184:Transplantation, Homologous
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin