title: The role of alphabeta- and gammadelta-T cells in allogenic donor marrow on engraftment, chimerism, and graft-versus-host disease.
abstract: BACKGROUND
  We previously characterized a facilitating cell (FC) in mouse marrow that enables engraftment of allogeneic hematopoietic stem cells (HSCs) without causing graft-versus-host disease (GVHD). The FC shares some cell surface molecules with T cells (Thy1+, CD3epsilon+, CD8+, CD5+, and CD2+) but is T-cell receptor (TCR) negative. Historically, depletion of CD3+ or CD8+ cells from rat marrow was associated with an increased rate of failure of engraftment. In this study, we evaluated whether depletion of alphabeta- and gammadelta-TCR(+) T cells from donor marrow would retain engraftment potential yet avoid GVHD.
  
  
  METHODS
  Wistar-Furth rats were conditioned with 950 cGy of total body irradiation and transplanted with ACI bone marrow processed to remove either alphabeta-TCR(+), gammadelta-TCR(+), or alphabeta- plus gammadelta-TCR(+) T cells. Recipients were typed for chimerism at 28 days and monthly thereafter.
  
  
  RESULTS
  Recipients of marrow depleted of alphabeta- (group A), gammadelta- (group B), or alphabeta- and gammadelta-TCR(+) T cells (group C) engrafted and had an average chimerism level of 73.0+/-8.3%, 92.3+/-9.2%, and 46.3+/-32.8%, respectively. Aggressive T-cell depletion did not remove the FC population (CD8+/CD3+/TCR(-)). Group A and group B both developed GVHD, with a higher incidence of GVHD in group B compared to group A. None of the recipients in group C developed GVHD.
  
  
  CONCLUSIONS
  These data demonstrate that depletion of T cells from rat marrow does not impair engraftment of HSCs, indirectly supporting the existence of FCs in rat marrow. Moreover, donor alphabeta- and gammadelta-TCR(+) T cells contribute to GVHD in a nonredundant fashion, although alphabeta-TCR(+) T cells are more potent as the effector cells. Finally, the level of donor chimerism is influenced by the composition of the graft, because recipients of marrow that contain alphabeta-TCR(+) T cells exhibited significantly higher donor chimerism compared to recipients of marrow depleted of both alphabeta- and gammadelta-TCR(+) T cells.
authors.affiliation: Institute for Cellular Therapeutics, University of Louisville, 570 South Preston Street, Suite 404, Louisville, KY 40202, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.forename: D E
authors.initials: DE
authors.lastname: Cramer
authors.forename: M B
authors.initials: MB
authors.lastname: Ray
authors.forename: P M
authors.initials: PM
authors.lastname: Chilton
authors.forename: X
authors.initials: X
authors.lastname: Que
authors.forename: S T
authors.initials: ST
authors.lastname: Ildstad
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology*; D006086:Graft vs Host Disease / Q000209:etiology* / Q000517:prevention & control; D016027:Heart Transplantation / Q000276:immunology; D007937:Leukapheresis; D051381:Rats; D011916:Rats, Inbred F344; D011920:Rats, Inbred WF; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D013601:T-Lymphocytes / Q000502:physiology*; D014019:Tissue Donors; D018183:Transplantation Chimera; D023001:Transplantation Tolerance; D014184:Transplantation, Homologous
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta