title: Lymphoid sequestration of alloreactive memory CD4 T cells promotes cardiac allograft survival.
abstract: Memory T cells specific for donor Ags present a unique challenge in transplantation. In addition to expressing robust immune responses to a transplanted organ, memory T cells may be resistant to the effects of immunosuppressive therapies used to prolong graft survival. In this study, we explore the possibility of controlling deleterious donor-reactive memory CD4 T cells through lymphoid sequestration. We showed that sphingosine 1-phosphate receptor-1 agonist FTY720 induces relocation of circulating memory CD4 T cells into secondary lymphoid organs. Lymphoid sequestration of these donor-reactive memory CD4 T cells prolonged survival of murine heterotopic cardiac allografts and synergizes with conventional costimulatory blockade to further increase graft survival. Despite limited trafficking, memory CD4 T cells remain capable of providing help for the induction of anti-donor CD8 T cell and alloantibody responses. Elimination of antidonor humoral immunity resulted in indefinite allograft survival proving the pathogenicity of alloantibody under these conditions. Overall, this is the first demonstration that FTY720 influences memory CD4 T cell trafficking and attenuates their contribution to allograft rejection. The data have important implications for guiding FTY720 therapy and for designing combinatorial strategies aimed at prolonging allograft survival in sensitized transplant patients with donor-specific memory T cells.
authors.affiliation: Department of Immunology, The Cleveland Clinic Foundation, Cleveland OH 44195, USA.
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yifa
authors.initials: Y
authors.lastname: Chen
authors.forename: Robert L
authors.initials: RL
authors.lastname: Fairchild
authors.forename: Peter S
authors.initials: PS
authors.lastname: Heeger
authors.forename: Anna
authors.initials: A
authors.lastname: Valujskikh
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D000068876:Fingolimod Hydrochloride; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology* / Q000473:pathology; D007156:Immunologic Memory; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007518:Isoantibodies / Q000096:biosynthesis; D008221:Lymphoid Tissue / Q000187:drug effects / Q000276:immunology*; D008297:Male; D051379:Mice; D020297:Mice, Congenic; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011409:Propylene Glycols / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014184:Transplantation, Homologous
chemical_list: D007166:Immunosuppressive Agents; D007518:Isoantibodies; D011409:Propylene Glycols; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine