NISHIMURA Yousuke Faculty of Medicine, Department of Cardiovascular Surgery, Kyushu University, assistant professor, 医学部, 助手 (50301338)
TOMITA Yukihiro Faculty of Medicine, Department of Cardiovascular Surgery, Kyushu University, assistant professor, 医学部, 助手 (90180174)
|Budget Amount *help
¥3,300,000 (Direct Cost : ¥3,300,000)
Fiscal Year 1999 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1998 : ¥2,500,000 (Direct Cost : ¥2,500,000)
These results indicate that the suboptimal conditioning (SC+100mg/kg CP) of CP-induced tolerance with 1x10ィイD28ィエD2 SC and 100 mg/kg CP can permit heart allograft tolerance without the development of CAV or accumulation of mRNAs for Th1 or Th2 cytokines. Furthermore, the induction of skin allograft tolerance is more difficult than the prevention of post-transplant CAV.
Post-transplant cardiac allograft vasculopathy (CAV) is a key manifestation of chronic rejection in heart transplant recipients and impairs long-term graft outcome. In the present study, we have investigated whether CAB can be prevented by the treatment of cyclophosphamide (CP) -induced tolerance in a murine CAV model of H-2 matched AKR (H-2ィイD2kィエD2 ; Thy1.1, Mls-1ィイD2aィエD2) into C3H (H-2ィイD2kィエD2 ; Thy1.1, Mls-1ィイD2bィエD2) mice. When C3H mice were grafted with H-2 matched AKR heart grafts (HG), most of AKR HG survived over 100 days, but all were rejected within 260 days after grafting. CAV developed in all AKR HG. When C
3H mice were primed i.v. with 1x10ィイD28ィエD2 AKR(H-2k_) spleen cells (SC) and treated i.p. with 200 mg/kg CP, the survival of AKR hearts was prolonged permanently in tolerogen-specific fashion, as observed in that of AKR skins. By this treatment, both minimal degree of mixed chimerism and clonal destruction of Mls-1ィイD2aィエD2-reactive CD4+Vβ6+ T cells in the periphery were observed. Furthermore, post-transplant CAV did not develop in the grafted AKR hearts. When AKR SC and 100mg/kg CP were used as the conditioning, AKR HG were accepted permanently, but survival of AKR skin grafts was mildly prolonged. The clonal destruction of CD4+Vβ6+ T cells was induced in the periphery. A minimal degree of mixed chimerism was detectable at 4 weeks after AKR SC and 100mg/kg CP treatment, but hardly became detectable at 20 week. In the AKR HG of C3H mice treated with AKR SC and 100mg/kg CP, post-transplant CAV did not develop, either. Second set skin grafts from donor AKR mice survived in a tolerogen-specific fashion over 100 days in 10/10 C3H mice treated with AKR SC and 200mg/kg CP and accepting AKR HG over 200 days, and 8/10 C3H mice treated with AKR SC and 100mg CP and accepting AKR HG over 200 days. In order to further elucidate the nature of tolerance induced with AKR SC and CP, PCR assay was performed. Neither Th1 (IL-2, g-UFN) nor Th2 (Il-4, IL-10) cytokines were accumulated at 4 weeks post-heart grafting in the AKR HG of tolerant C3H mice treated with both AKR SC and 200mg/kg CP and AKR SC and 100mg/kg CP.
(ii)CP誘導性免疫寛容で観察されるキメラ状態の質的量的解析:非移植抗原であるLy5(CD45)抗原のみの違うCongenicマウスを用いて解析を行ったところ、本寛容系で誘導されるキメラ状態はリンパ系のみであり、骨髄レベルではないことが明らかとなった(Yoshikawa et al,Transplant Proc 1998,1999,Immunobiology,In press)。
(iii)CPの分割投与による副作用軽減効果の試み:3分割(66mg/kgx3)投与によっても本寛容系は誘導可能であり、3分割することにより細菌(Pseudomonas菌)に対する感染抵抗性が得られた(Zhang,et al.Transplantation 1997).
(iv)MHC抗原の違うB10.D2(H-2d)→B10(H-2b)においてキメラ状態・皮膚移植片寛容状態の誘導:(ii)の結果に基き骨髄抑制作用のより強いBusulfan(BU;致死量250mg/kg)+Donor骨髄細胞をCP誘導性免疫寛容に加えることにより、永久的なキメラ状態と皮膚片に対する寛容状態を誘導することが可能となった(Tomita et al,submitted for publication)。 Less