title: Ex vivo rapamycin generates apoptosis-resistant donor Th2 cells that persist in vivo and prevent hemopoietic stem cell graft rejection.
abstract: Because ex vivo rapamycin generates murine Th2 cells that prevent Graft-versus-host disease more potently than control Th2 cells, we hypothesized that rapamycin would generate Th2/Tc2 cells (Th2/Tc2.R cells) that abrogate fully MHC-disparate hemopoietic stem cell rejection more effectively than control Th2/Tc2 cells. In a B6-into-BALB/c graft rejection model, donor Th2/Tc2.R cells were indeed enriched in their capacity to prevent rejection; importantly, highly purified CD4+ Th2.R cells were also highly efficacious for preventing rejection. Rapamycin-generated Th2/Tc2 cells were less likely to die after adoptive transfer, accumulated in vivo at advanced proliferative cycles, and were present in 10-fold higher numbers than control Th2/Tc2 cells. Th2.R cells had a multifaceted, apoptosis-resistant phenotype, including: 1) reduced apoptosis after staurosporine addition, serum starvation, or CD3/CD28 costimulation; 2) reduced activation of caspases 3 and 9; and 3) increased anti-apoptotic Bcl-xL expression and reduced proapoptotic Bim and Bid expression. Using host-versus-graft reactivity as an immune correlate of graft rejection, we found that the in vivo efficacy of Th2/Tc2.R cells 1) did not require Th2/Tc2.R cell expression of IL-4, IL-10, perforin, or Fas ligand; 2) could not be reversed by IL-2, IL-7, or IL-15 posttransplant therapy; and 3) was intact after therapy with Th2.R cells relatively devoid of Foxp3 expression. We conclude that ex vivo rapamycin generates Th2 cells that are resistant to apoptosis, persist in vivo, and effectively prevent rejection by a mechanism that may be distinct from previously described graft-facilitating T cells.
authors: Experimental Transplantation and Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. marriottj@mail.nih.gov
authors: Jacopo
authors: J
authors: Mariotti
authors: Jason
authors: J
authors: Foley
authors: Unsu
authors: U
authors: Jung
authors: Todd
authors: T
authors: Borenstein
authors: Nermina
authors: N
authors: Kantardzic
authors: Soo
authors: S
authors: Han
authors: Joshua T
authors: JT
authors: Hanson
authors: Elaine
authors: E
authors: Wong
authors: Nicole
authors: N
authors: Buxhoeveden
authors: Jane B
authors: JB
authors: Trepel
authors: Antonio Tito
authors: AT
authors: Fojo
authors: William
authors: W
authors: Telford
authors: Daniel H
authors: DH
authors: Fowler
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006084:Graft Rejection / Q000517:prevention & control*; D006086:Graft vs Host Disease / Q000276:immunology / Q000628:therapy; D018380:Hematopoietic Stem Cell Transplantation; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D051379:Mice; D020297:Mice, Congenic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases; D018418:Th2 Cells / Q000187:drug effects* / Q000276:immunology / Q000637:transplantation
chemical_list: D051017:Apoptosis Regulatory Proteins; D016207:Cytokines; D007166:Immunosuppressive Agents; D011494:Protein Kinases; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus