title: Chimeric acceleration by donor CD4+CD25+T-reg depleted fraction in splenocyte transplantation.
abstract: BACKGROUND
  We have established a splenocytic chimera model that can induce donor-specific tolerance and reconstitute the recipient immune system by donor splenocytes.
  
  
  OBJECTIVE
  To accelerate such reconstitution, we investigated the role of donor-derived CD4(+)CD25(+) regulatory T-cells (T-reg).
  
  
  METHODS
  We established C3H/B6D2F1 mixed bone marrow chimeras in lethally irradiated C3H mice. We transplanted skin grafts from C57BL/6 mice 30 d later. After an additional 30 d, we transplanted the following types of splenocytes from B6C3F1 mice: total splenocytes (group A), CD4(+)CD25(+) T-reg depleted splenocytes (group B), CD8(+)-depleted splenocytes (group C), and CD4(+)-depleted splenocytes (group D). We assessed class I major histocompatibility complex, percentage of chimeric cells in peripheral blood, and survival of skin grafts in each group.
  
  
  RESULTS
  Group A and B mice switched to splenocytic chimeras, permitting the long-term survival of skin grafts. The proportions of H-2K(b+)H-2K(k-) cells in group B were significantly lower than those in group A on day 14 (0.47% ± 0.68% versus 9.49% ± 8.30%; P = .01) and day 21 (0.16% ± 0.25% versus 3.35% ± 2.78%; P = .01). The initial increase in the proportion of H-2K(b+)H-2K(k+) double-positive cells in group B was faster than that in group A (from 0.33% ± 0.10% versus. 0.39% ± 0.14% before splenocyte injection to 39.03% ± 30.50% versus 10.73% ± 11.54% on day 7; P = .02). The initial increase in the proportion of CD8(+) T-cells was faster in group B than in group A (from 2.72% ± 0.52% versus 2.49% ± 1.07% before splenocyte injection to 29.61% ± 26.72% versus 4.92% ± 1.56% on day 7; P = .04).
  
  
  CONCLUSIONS
  The depletion of CD4(+)CD25(+) T-reg fraction in donor splenocytes can accelerate switching to splenocytic chimera.
authors.affiliation: Department of Digestive Surgery, Nihon University School of Medicine, 30-1, Ohyaguchi Kami-machi, Itabashi-ku, Tokyo 173-8610, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kutsuna
authors.forename: Shintaro
authors.initials: S
authors.lastname: Yamazaki
authors.forename: Teruo
authors.initials: T
authors.lastname: Kaiga
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Inagaki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Akira
authors.initials: A
authors.lastname: Kanamoto
authors.forename: Shunji
authors.initials: S
authors.lastname: Okada
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology*; D015704:CD4 Antigens / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D006085:Graft Survival / Q000276:immunology; D007108:Immune Tolerance / Q000276:immunology; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008212:Lymphocyte Depletion / Q000379:methods*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D016038:Skin Transplantation / Q000276:immunology*; D013154:Spleen / Q000166:cytology* / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D018183:Transplantation Chimera / Q000276:immunology; D023001:Transplantation Tolerance / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D053645:Interleukin-2 Receptor alpha Subunit