大鼠胸腺内注射同种抗原对甲状旁腺移植物存活的影响

目的　改善甲状旁腺移植物的存活时间。方法　用SDLewis及DA大鼠进行甲状旁腺移植实验。由供体Lewis大鼠的脾细胞提取抗原。按照不同的抗原注射途径（尾静脉、门静脉及胸腺内）,是否合用抗淋巴细胞血清及第3品系大鼠的甲状旁腺移植共分为9组。结果　胸腺内注射抗原结合抗淋巴细胞血清的应用，使甲状旁腺移植物的平均存活期达到（196.00±3.96）d，与其他各组相比差异有非常显著性（P＜0.01）。结论　大鼠胸腺内注射抗原结合抗淋巴细胞血清的应用成功地诱导受体产生了供体特异性免疫耐受。     

免疫毒素及可溶性抗原诱导胰岛移植耐受

目的　通过静脉注入抗ＣＤ４ 、ＣＤ８ 免疫毒素及供体可溶性抗原诱导胰岛移植物免疫耐受。方法　供、受体分别为Ｗｉｓｔａｒ 大鼠和ＳＤ大鼠， 移植前１４ 天、７ 天分别将免疫毒素各２００ μｇ， 供体可溶性抗原５００ μｇ 经静脉注入受体， 然后将供体５００ 个胰岛移植于受体（ 糖尿病大鼠）左侧肾包膜下。结果　用免疫毒素及供体可溶性抗原联合处理组胰岛移植物存活时间显著延长（ Ｐ＜ ０ ．０１） ， 而单独应用抗ＣＤ４ 、ＣＤ８ 免疫毒素或供体可溶性抗原组仅能获得胰岛移植物存活时间轻度延长。结论　抗ＣＤ４、ＣＤ８ 免疫毒素及供体可溶性抗原联合应用可以诱导供体特异性免疫耐受     

转染细胞毒性T淋巴细胞相关抗原4免疫球蛋白基因的同供体大鼠树突状细胞对胰岛移植物存活的影响

目的　探讨转染细胞毒性T淋巴细胞相关抗原4(转染CTLA4Ig基因)的同供体大鼠DC细胞对同种大鼠胰岛移植的影响。方法　链尿菌素(STZ) 60mg/kg体重腹腔内注射制作SD大鼠糖尿病模型,胶原酶法分离、Ficoll 40 0密度梯度离心法纯化胰岛,GM CSF +IL 4诱生培育的方法,获得高纯度的DC ,含目的基因CTLA4Ig重组腺病毒AdvCTLA4Ig ,转染同供体DC细胞,与胰岛细胞同时移植于糖尿病受体大鼠肾包膜下,免疫组织化学、Dot ELISA、逆转录 聚合酶链反应(RT PCR)检测CTLA4Ig基因在实验组和对照组DC细胞中的表达,并检测受体大鼠的血糖浓度变化,同时观察受体存活情况。结果　实验组DC细胞有CTLA4Ig表达,而对照组DC细胞没有CTLA4Ig表达,实验组正常血糖维持时间(17.3±2 .4)d较对照组(10 .1±1.5 )d、空白对照组(8.3±1.2 )d显著延长,实验组、对照组和空白对照组受体大鼠存活天数分别为(3 4.5±3 .4)d、(14 .7±2 .3 )d和(11.2±1.4)d ,实验组高于对照组(P <0 .0 1)。结论　表达CTLA4Ig基因的DC细胞可能诱异胰岛移植免疫耐受,延长胰岛移植物的存活时间     

诱导免疫耐受预防大鼠肾脏移植排斥反应的研究

目的 探讨具有临床应用前景的移植耐受诱导方法。方法 以Lewis大鼠和DA大鼠分别作为肾脏移植的受体和供体,采用注射抗淋巴细胞血清（ALS）、输入供体骨髓细胞（BMT）和环磷酰胺（Cp）注射方法进行移植耐受诱导,观察肾脏移植物的存活情况及受体对供体细胞抗原免疫应答改变。结果 经耐受诱导的大鼠肾脏移植物存活时间明显延长,7只鼠中5只移植物存活73－90 d时仍无排斥反应迹象,混合淋巴细胞反应及诱导迟发型超敏反应表现为供体特异性降低。结论 诱导免疫耐受预防肾脏移植排斥反应具有重要的临床意义,此方法有一定的临床应用前景。     

供体脾细胞胸腺注射对大鼠肢体移植存活的研究

目的 :通过大鼠肢体移植模型 ,旨在分析供体脾细胞注射对大鼠肢体移植中免疫耐受的诱导作用。方法 :选择雄性Wistar和SD大鼠为供、受体 ,对照组为胸腺注射脾细胞培养液 ,实验组为供体脾细胞注射 ,进行了 1 6例异体肢体移植动物实验。观察大鼠移植肢体排斥反应时间及存活时间。结果 :对照组肢体平均存活时间为 ( 9.38± 1 .92 )d ;实验组移植肢体存活时间为 ( 1 5.38± 2 .97)d。结论 :供体脾细胞胸腺注射大鼠肢体移植术后能够明显延长移植肢体的存活时间。     

免疫毒素及可溶性抗原诱导胰岛素移植耐受

目的 通过静脉注入抗ＣＤ４、ＣＤ８免疫毒素及供体可溶性抗原诱导胰岛植物免疫耐受。方法 供、受体分别为Ｗｉｓｔａｒ大鼠和ＳＤ大鼠,移植前１４天,７天分别将免疫毒素各２００μｇ,供体可溶性抗原５００μｇ经静脉注入受体,然后将供体５００个胰岛移植于受体（糖尿病大鼠）左侧肾包膜下。结果 用免疫毒素及供体可溶性抗原联合处理组胰岛移植物存活时间显著延长（Ｐ〈０．０１）。而单独应用抗ＣＤ４、ＣＤ８免疫毒素或供体     

甲状旁腺移植免疫耐受实验研究

本文主要研究以SD大鼠作供体,以Wistar大鼠为受体的甲状旁腺移植免疫耐受的实验。通过本实验研究揭示移植前输注供体肝细胞可诱导免疫耐受产生;而输注适当剂量的肝细胞免疫抗原,对移植物的存活期长短有重要作用。CsA可明显改善器官移植的存活期;它在抗原暴露前应用可抑制受体T细胞的活性,使受体的免疫系统对移植物产生耐受性。供体肝细胞输注及CsA联合使用,本组无1例动物达到长期存活,这可能与加用CsA后干扰体内免疫调节机能有关。     

MHC基因胸腺转移诱导异基因小鼠皮肤移植免疫耐受

目的通过胸腺内注射质粒ＰＸＮ（Ｎ２Ｂ１９Ｈ２Ｋｂ）,表达外源性主要组织相容性抗原复合物（ＭＨＣ）抗原,以小鼠皮肤移植为模型,诱导移植免疫耐受,为免疫耐受提供理论和实验依据。方法应用逆转录病毒载体介导的基因转移技术,通过ＢＡＬＡ／Ｃ胸腺内注射质粒ＰＸＮ（Ｎ２Ｂ１９Ｈ２Ｋｂ）,将外源性ＭＨＣ基因转移到胸腺细胞,１４天后行异基因小鼠皮肤移植。应用聚合酶链反应（ＰＣＲ）,反转录聚合酶链反应（ＲＴＰＣＲ）,单克隆抗体免疫荧光染色流式细胞仪检测胸腺细胞ＤＮＡ,ｍＲＮＡ和ＭＨＣ蛋白质表达。结果外源性ＭＨＣ基因已整合到靶细胞染色体ＤＮＡ并有效地转录,胸腺细胞表面有外源性ＭＨＣ分子表达,转染效率为５％,胸腺内注射质粒ＰＸＮ（Ｎ２Ｂ１９Ｈ２Ｋｂ）能明显延长异基因小鼠的皮肤移植时间,平均２７天,对照为１０天（Ｐ＜０００１）。受体鼠脾细胞对ＣｏｎＡ的增殖反应在正常范围。结论供体鼠ＭＨＣ基因转移至受体鼠胸腺诱导了对供体皮肤移植的免疫耐受。     

胸腺内注射异基因抗原诱导鼠神经移植免疫耐受的实验研究

目的探讨小鼠胸腺内注射异基因抗原在同种异体异基因坐骨神经移植免疫耐受中的作用。方法自供体小鼠C57BL／6的脾细胞中提取MHC抗原注人受体鼠Balb／c小鼠胸腺内，于2周后移植供体鼠坐骨神经。48只Balb／c小鼠随机分为4组，A组（胸腺内注射组）、B组（自体神经移植组）、C组（冷冻异体神经移植组）、D组（异体神经移植加用免疫抑制剂组）。于3周后进行电生理学、组织学、免疫学检测。结果A组运动神经传导速度（38．23m／s）与D组（36．39m／s）相比无显著性差异（P〉0．05），组织学、电镜、免疫学（混合淋巴细胞培养及迟发性超敏反应）检测结果均证实B组分别优于A组、D组和C组。结论胸腺内注射异基因MHC抗原可诱导大鼠对异体坐骨神经移植的特异性免疫耐受。     

转化生长因子beta1修饰供体树突状细胞对大鼠肾脏移植物存活的影响

目的:观察转化生长因子(TGF)beta1修饰供体树突状细胞的输注对大鼠肾脏移植物存活的影响,以及诱导大鼠产生抗原特异性免疫耐受的情况,并探讨其机制。方法:通过逆转录病毒载体,将TGFbeta1基因转染体外培养的供体树突状细胞,术前输注给肾移植受体,用RTPCR和免疫荧光观察目的基因的表达,用3HTdR观察供体树突状细胞对受体T细胞的激活,观察移植物存活情况。结果:输注转基因供者树突状细胞的肾移植受体大鼠,移植物存活时间比对照组明显延长(P≤0.05)。3HTdR观察供体树突状细胞对受体T细胞的激活显示树突状细胞对受体淋巴细胞的激活明显比对照组减弱(P≤0.01)。结论:TGFbeta1的供者树突状细胞的输注可以明显延长大鼠肾脏移植物存活,并且抑制了转基因的树突状细胞对受体T细胞的激活。     

Donor-derived soluble MHC antigens plus low-dose cyclosporine induce transplantation unresponsiveness independent of the thymus by down-regulating T cell-mediated alloresponses in a rat transplantation model.

BACKGROUND: In vitro, soluble MHC (sMHC) antigens modulate and induce apoptosis in alloreactive and antigen-specific T cells, demonstrating their potency to regulate T cell-mediated immune responses. However, their efficacy to regulate immunological responses in vivo remains unclear. Here, we report that repetitive intraperitoneal injection of recombinant Lewis rat-derived MHC class I antigens in Dark Agouti (DA) rats modulates alloreactivity. METHODS: RT1.A1 (Lewis derived) genes were cloned into mammalian expression vectors, and RT1.Aa (DA derived) genes were used to transfect a rat myeloma cell line. RT1.A1 molecules were injected intraperitoneally in DA recipients that subsequently underwent transplantation with Lewis-derived cardiac allografts. RESULTS: Soluble class I antigens were secreted by the transfected cells and were shown to be heterodimeric, peptide-loaded, and conformationally folded. Injection of donor-derived soluble MHC significantly reduced the ability of recipient animals to mount a cytotoxic T-cell response to donor-derived tissue. More interestingly, this treatment significantly prolonged donor-graft survival and allowed 60% of treated animals to develop graft tolerance (>120 days), when donor sMHC were combined with a single subtherapeutic dosage of cyclosporine. Thymectomy of recipient animals before transplantation did not interfere with induction of peripheral tolerance. CONCLUSIONS: Donor-derived sMHC are potential tolerogens for down-regulating the cytotoxic T-cell response of animals that undergo transplantation. Thus, these data provide for the first time a rationale for the application of directly injected sMHC in vivo to down-regulate immunological responses and aid the induction of graft tolerance.     

Indirect allorecognition in acquired thymic tolerance: induction of donor-specific tolerance to rat cardiac allografts by allopeptide-pulsed host dendritic cells

BACKGROUND: Presentation of peptides either by recipient or donor MHC molecules displayed on the surface of antigen-presenting cells is an essential element in the induction of T cell responses to transplant antigens. The finding that intrathymic (IT) injection of an immunodominant peptide induces acquired thymic tolerance suggests an indirect pathway of allorecognition in the thymus. To address this theory, we studied the effects of IT injection of host bone marrow (BM)-derived dendritic cells (DC)-pulsed with the immunodominant Wistar Furth (WF) MHC class I (RT1.Au) peptide 5 (93-109) on cardiac allograft survival in the WF-to-ACI rat combination. METHODS: DC were propagated from cultures of ACI (recipient) bone marrow (BM) maintained in a medium supplemented with granulocyte-macrophage colony-stimulating factor and IL-4. The BM-derived DC after 8 days of culture were pulsed in vitro with a single WF MHC class I peptide (Residue 93-109) with the dominant epitope, washed, and injected into the thymus of ACI rats. The ACI recipients received donor-type (WF) or 3rd party (Lewis) cardiac allografts 7 days after IT immunization with peptide-pulsed DC. RESULTS: BM-derived DC cultured in granulocyte-macrophage colony-stimulating factor and interleukin-4 for 8 days have a strong allostimulatory ability and present peptide 5 to naive syngeneic T cells in mixed lymphocyte reaction. IT inoculation of 300 microg RT1.Au peptide 5 combined with transient antilymphocyte serum immunosuppressive therapy induced donor-specific tolerance to cardiac allografts. Extension of this finding to peptide-pulsed self DC showed that IT injection of peptide 5-pulsed host DC consistently led to permanent acceptance (>150 days) of donor-type (WF) cardiac allografts, whereas third-party (Lewis) grafts were acutely rejected. The long-term unresponsive recipients challenged with second-set grafts accepted permanently (>100 days) donor-type(WF) grafts while rejecting third-party (Lewis) grafts without the rejection of the primary WF grafts. CONCLUSION: This novel finding that allopeptide-pulsed host DC induces tolerance to cardiac allografts suggests that the induction of acquired tolerance is dependent on the indirect allorecognition pathway. The results further suggest that genetically engineered DC expressing donor MHC class I or II molecules or a peptide analogue might have therapeutic potential in the induction of transplant tolerance and in the treatment of autoimmune diseases.     

MHC class II presenting cells are necessary for the induction of intrathymic tolerance.

OBJECTIVE: This study determined the form of cellular donor MHC alloantigen necessary for the induction of intrathymic tolerance. BACKGROUND: The authors have achieved indefinite donor-specific tolerance, to a fully MHC-disparate rat heterotopic cardiac allograft, after the pretransplant intrathymic injection of unfractionated donor splenocytes and a single injection of rabbit anti-rat lymphocyte serum (ALS), without subsequent immunosuppression. METHODS: Male 4-12-week-old Buffalo (RT1b) rats underwent an intrathymic injection of either fractionated Lewis (RT1(1)) red blood cells (purified by Ficoll gradient) or T lymphocytes (purified by nylon wool column and plastic adherence), both of which express only MHC class I alloantigens, or B lymphocytes, macrophages, and dendritic cells (purified by plastic adherence) which express both MHC class I and class II alloantigens. At the completion of alloantigen injection the Buffalo recipient rats were given 1 ml of ALS intraperitoneally. Twenty-one days later a heterotopic Lewis heart was transplanted. RESULTS: The intrathymic injection of the fractions of Lewis MHC class I and class II expressing B lymphocytes, macrophages, and dendritic cells induced a donor-specific tolerance that resulted in indefinite Lewis cardiac allograft survival (MST > 125 days) in all recipients without further immunosuppression, whereas groups receiving MHC class I expressing red blood cell or T lymphocyte injections plus ALS rejected Lewis cardiac allografts with a MST of 7.3 and 16.5 days, respectively, thus indicating that the MHC class II expressing cell is necessary for the induction of intrathymic tolerance. Buffalo recipients with a long-term surviving Lewis cardiac allograft, after Lewis MHC class II expressing cells were still able to reject a third-party heterotopic ACI (RT1a) cardiac allograft in normal time (MST = 7.0 days), but did not reject a second Lewis cardiac allograft (MST > 100 days). Additionally, the intrathymic injection of MHC class II expressing cells resulted in decreased interleukin-2 (IL-2) production and an 80% decrease in in vitro donor-specific cell mediated cytotoxicity, whereas the cytolytic response to a third party was unaltered. CONCLUSION: Donor MHC class II, and not class I, expressing cells are the cells in donor splenocytes, injected intrathymically, responsible for the development of donor-specific allograft tolerance.     

Soluble donor MHC class I gene transfer to thymus promotes allograft survival in a high-responder heart transplant model

Thymic selection of self and non-self-reactive lymphocytes is a process that may be targeted to induce donor-specific immunologic unresponsiveness in organ transplantation. In the present study, gene transfer was used to preexpose the recipient thymus to soluble donor-specific MHC class I molecules prior to heart transplantation in the high-responder ACI (RT1^a) to Lewis (RT1^l) rat strain combination. Specifically, cultured Lewis hepatocytes were transfected with DNA encoding a secreted form of the donor allo-MHC class I antigen, RT1.A^a. Seven days prior to ACI heart transplantation, genetically altered recipient-strain hepatocytes were injected into the thymus of Lewis recipients which also received a dose of antilymphocyte serum (ALS). Results showed that treatment with both ALS and soluble donor MHC-expressing hepatocytes prolonged transplant survival time by twofold, compared to injection of control hepatocytes and ALS. Therefore, intrathymic gene therapy delivery of soluble donor MHC molecules may be useful for promoting allograft survival in heart transplantation.     

Donor MHC class I peptides in conjunction with self-epitopes induce donor-specific tolerance in a dose-dependent manner but unable to abrogate chronic rejection

Understanding specific tolerance mechanisms is a primary goal of transplantation science. We have previously shown that hosts treated with MHC class I protein have donor sequences in the alpha1-helix of the alpha1 domain on a background of self-epitopes, resulting in the development of donor-specific tolerance. However, the nature of class I alloantigenic determinants that regulate the alloimmune response remains unclear. The alpha1-helical sequence of RT1.A,1 which shares RT1.A(u) sequences, was substituted in the RT1.A(a) molecule to produce the composite [alpha1h(l/u)]-RT1.A(a) MHC class I allochimeric molecule. Immunodominant epitopes were identified within the hypervariable region of the alpha1 domain of RT1.A(a) (ACI), RT1.Al (Lewis, LEW), and RT1.A(u) (Wistar Furth [WF]). To clarify the mechanisms of tolerance development through presentation of donor-type immunogenic epitopes and cryptic self-epitopes we used synthetic peptides corresponding to donor immunogenic determinants with peptides derived from recipient self-sequences (RT1.A(a)--aa 10 to 49 P1 and 91 to 120 P3; and P2 RT1.A(l/u) 50 to 90). ACI recipients of LEW and WF cardiac allografts were injected through the portal vein (PV) at day 0 with four doses (2, 0.5, 0.25, and 0.125 mg/rat) of three peptide mixtures in conjunction with subtherapeutic CsA (10 mg/kg for 3 days). Allograft survival was strongly dose-dependent. Only low-dose regimens were consistent in tolerance induction, but such therapy did not abrogate development of chronic rejection (CR), unlike allochimeric therapy with soluble MHC class I protein. Different effects of protein or synthetic peptide therapies on development of CR suggest that development of specific tolerance is an active immunologic process and it depends on the form of allogeneic epitopes presented.     

Allospecific Rejection of MHC Class I‐Deficient Bone Marrow by CD8 T Cells

Avoidance of long‐term immunosuppression is a desired goal in organ transplantation. Mixed chimerism offers a promising approach to tolerance induction, and we have aimed to develop low‐toxicity, nonimmunodepleting approaches to achieve this outcome. In a mouse model achieving fully MHC‐mismatched allogeneic bone marrow engraftment with minimal conditioning (3 Gy total body irradiation followed by anti‐CD154 and T cell–depleted allogeneic bone marrow cells), CD4 T cells in the recipient are required to promote tolerance of preexisting alloreactive recipient CD8 T cells and thereby permit chimerism induction. We now demonstrate that mice devoid of CD4 T cells and NK cells reject MHC Class I‐deficient and Class I/Class II‐deficient marrow in a CD8 T cell–dependent manner. This rejection is specific for donor alloantigens, since recipient hematopoiesis is not affected by donor marrow rejection and MHC Class I‐deficient bone marrow that is syngeneic to the recipient is not rejected. Recipient CD8 T cells are activated and develop cytotoxicity against MHC Class I‐deficient donor cells in association with rejection. These data implicate a novel CD8 T cell–dependent bone marrow rejection pathway, wherein recipient CD8 T cells indirectly activated by donor alloantigens promote direct killing, in a T cell receptor–independent manner, of Class I‐deficient donor cells.     

IgG alloantibody responses to donor-specific blood transfusion in different rat strain combinations as a predictor of renal allograft survival.

Donor-specific blood transfusion prolongs the survival of fully allogeneic ACI (RT1a) renal allografts in PVG (RT1c) recipients from 7-10 days to greater than 100 days. We have observed significant differences in the alloantibody (Ab1) responses to ACI renal allografts in control and DSBT-treated PVG recipients: DSBT is associated with decreased IgG and IgM alloantibody circulating in serum, deposited in the allograft, and produced in culture by splenocytes. In the present studies the effects of DSBT on alloantibody production and renal allograft survival were extended to examine other recipient strains: F344 (RT1lv1), BN (RT1n), W/F (RT1u) and LEW (RT1l). Animals of each recipient strain were injected i.v. with 0.5 ml of ACI blood alone or followed by a renal allograft. Studies on the kinetics of IgM and IgG alloantibody responses were performed by flow cytometry on lymphocytes from donor ACI, PVG, and PVG.R1 (RT1.Aa class I MHC antigen on PVG background) rats. In F344 and PVG rats, DSBT from ACI rats elicited a transient IgM response that peaked at day 7 and was not followed by a switch to IgG. In control PBS transfused F344 recipients, an ACI renal allograft stimulated both IgM and IgG alloantibody production. DSBT pretreatment significantly decreased circulating IgG alloantibody following ACI renal transplantation and prolonged graft survival in F344 recipients. In DSBT-treated F344 recipients that rejected ACI renal allografts acutely, small amounts of IgG (5-12 mode channel shift) were detected in sera harvested 7 days after transplantation, whereas almost no IgG was detected in the sera from DSBT treated F344 rats that accepted their renal allografts indefinitely. In contrast, DSBT alone from ACI to BN, W/F, or LEW strains elicited a transient IgM response that peaked at day 7 and was followed by a strong IgG response that peaked on days 10-14 and remained high through day 21. DSBT failed to prolong ACI renal allograft survival in any of these strains (survival less than 11 days in control and DSBT rats). The alloantibody response to DSBT in all five recipient strains examined was directed primarily to RT1.Aa class I MHC antigens, as determined by binding studies on lymphocytes from ACI, PVG and PVG.R1 rats and alloantibody blocking studies using biotinylated rat monoclonal antibodies to distinct epitopes of the RT1.Aa antigen. The relative magnitude of blocking of R2/10P and R2/15S binding by sera from BN, W/F, and LEW rats was: control allograft recipients greater than DSBT pretreated allograft recipients greater than DSBT alone.(ABSTRACT TRUNCATED AT 400 WORDS)     

Use of allochimeric proteins to mitigate graft-versus-host and host-versus-graft immune responses to rat small bowel allografts

BACKGROUND: We aimed to identify the polymorphic epitopes that mitigate graft-versus-host disease (GvHD) and host-versus-graft response (HvGR) toward rat small bowel allografts in rats. METHODS: We tailored class I major histocompatibility complex (MHC) allochimeric antigens encoding 10 al-helical (alpha(1h)l58-80-RT1.Aa) or 4 (alpha(1h)l/u62-69-RT1.Aa) polymorphic amino acids. In the GvHD model, ACI (RT1a) donors were pretreated (day -14) with an intrathymic injection of alpha(1h)l58-80-RT1.Aa, alpha(1h)l/u62-69-RT1.Aa, or RT1.Al protein, with or without simultaneous intravenous injection of anti-T-cell receptor R73 monoclonal antibodies. Wistar-Furth (WF; RT1u) donors were tested with a similar protocol. In the HvGR model, ACI recipients were treated with a protocol designed to induce transplantation tolerance toward WF heart allografts: a portal vein injection of alpha(1h)l/u62-69-RT1.Aa protein and cyclosporine (4 mg/kg, intramuscular; days 0-6). RESULTS: GvHD was prevented in all (ACI x LEW) F1 recipients (RT1a/l) by pretreating ACI donors with R73 monoclonal antibody and recipient RT1.Al or alpha(1h)l58-80-RT1.Aa protein. Similarly, pretreatment of WF donors with RT1.Aa protein also prevented GvHD in (ACI x WF) F1 recipients. However, in a combined GvHD/HvGR model, ACI recipient perioperative treatment designed to prevent HvGR only modestly prolonged WF small bowel allograft survival (27.7+/-5.3 days compared to 17.4+/-4.6 days in the cyclosporine-alone group). In contrast, application of the two protocols significantly prolonged WF allograft survival (55.6+/-34.6 days), with two of seven recipients surviving more than 100 days. CONCLUSION: Simultaneous inhibition of GvHD and HvGR significantly prolongs small bowel allograft survival.