Induction of Xeno-transplantation tolerance using mixed chimerism

背景：在非清髓性同种异体骨髓移植中，共刺激阻断可以避免重复T细胞消耗或胸腺照射，CD4消耗导致混合嵌合和供体特异性耐受。然而，混合嵌合对抗异种移植的潜力尚未得到评估。本文分析混合嵌合和共刺激阻断在异种心脏移植耐受中的作用。方法：C57BL/6小鼠在第1天接受抗cd8（2.43）和/或NK-1.1(PK136) + Thy-1.2（30-H12）单抗，第0天接受全身照射（TBI; 3 Gy），第0天接受100 × 10^6异种F344大鼠骨髓细胞（BMC）。同时给予抗cd40l单抗（MR1, 2mg, day0） 1次注射。在BMT后第0天进行异位心脏移植，以评估供者特异性耐受的诱导。用流式细胞术（FCM）检测供体细胞的植入情况。结果：未接受治疗的小鼠（n=6）在移植8天后出现排斥反应。单独接受TBI的小鼠（n=6）显示供体心脏（MST，中位生存时间=12）略有延长。抗CD8单抗组（第1天）、MR1组（第0天）+ TBI/BMT组（第0天）（n=6）和MR1组（第0天）+ TBI/BMT组（第0天）（n=5）小鼠均未发生长期混合嵌合，移植心脏在移植后不久出现排斥反应（MST分别为35天和33天）。接受抗nk1.1 /Thy1.2单克隆抗体（第1天）、MR1（第0天）加TBI/BMT（第0天）（n=6）的小鼠仅在BMT后早期出现混合嵌合，且移植物存活时间延长（MST=61天）。抗cd8 /NK1.1/Thy1.2单克隆抗体（第1天）、MR1（第0天）+ TBI/BMT（第0天）（n=6）小鼠最初出现混合嵌合，但在BMT后10周嵌合也消失。然而，这些小鼠接受供体大鼠心脏（MST bb0 250天）。仅抗cd8 /NK1.1/Thy1.2单抗（第1天）和MR1单抗（第0天）处理的小鼠（n=5）也显示供体大鼠心脏（MST=59）轻微延长，移植后105天出现排斥反应。结论：采用共刺激阻断和短暂混合嵌合可延长异种心脏移植存活。NK1.1和Thy1.2阳性细胞可能在诱导异种心脏移植的短暂混合嵌合和排斥反应中起重要作用。少

Background :Costimulatory blockade can obviate the need for repeated T cell depletion or thymic irradiation, CD4 depletion in an nonmyeloablative allogeneic bone marrow engraftment that leads to mixed chimerism and donor-specific tolerance. However, the potential of mixed chimerism against xenotransplantation has not been evaluated. Here we analyze the role of mixed chimerism and costimulatory blockade in xenogeneic heart transplantation tolerance.Methods :C57BL/6 mice received anti-CD8(2.43) and/or NK-1.1(PK136) plus Thy-1.2(30-H12)mAbs on day-1, total body irradiation(TBI ; 3 Gy)(day 0), and 100 × 10^6 xenogeneic F344 rat bone marrow cells(BMC). One injection of anti-CD40L mAb (MR1; 2mg, day0) was also given. Heterotopic heart transplantation was performed on day0 after BMT to assess induction of donor-specific tolerance. Donor cell engraftment was measured by flow cytometry (FCM) analysis.Results :Mice that received no treatment (n=6) rejected rat heart graft by 8 days. Mice receive … More d TBI alone (n=6) showed slightly prolongation of donor heart (MST, median survival time=12). Mice received anti- CD8 mAb (day-1), MR1 (day0) plus TBI/BMT(day0) (n=6) and mice received MR1 (day0) plus TBI/BMT(day0) (n=5) did not developed long-term mixed chimerism, and grafted heart were rejected soon after transplantation (MST=35day and 33day, respectively). Mice received anti-NK1.1/Thy1.2 mAbs (day-1), MR1(day0) plus TBI/BMT(day0) (n=6) developed mixed chimerism only early after BMT, and showed prolongation of graft survival (MST=61day). Mice received anti-CD8/NK1.1/Thy1.2 mAbs (day-1), MR1 (day0) plus TBI/BMT(day0) (n=6) initially developed mixed chimerism, however, those chimerism was also disappear by 10 weeks post BMT. However, those mice accepted donor rat heart (MST>250days). Mice treated only anti-CD8/NK1.1/Thy1.2 mAbs (day-1) and MR1 (day0) (n=5) also showed slight prolongation of donor rat heart (MST=59) and rejected by 105 days after transplantation.Conclusion :Prolongation of xenogeneic heart graft survival was achieved using costimulatory blockade and transient mixed chimerism. NK1.1 and Thy1.2 positive cells may play an important role in inducing transient mixed chimerism and rejection of xenogeneic heart graft. Less