The effects of size and site of origin of intestinal grafts on small-bowel transplantation in the rat

This study was initiated to evaluate the effects of varying the length and site of origin of small-intestine transplants on rejection and on graft-versus-host disease (GVHD). Eighty rats had heterotopic transplants performed with systemic venous drainage of the grafts. The host native bowel was left in situ and no immunosuppressive agents were used. Twenty male Lewis inbred (LEW) rats who received isogenic grafts survived without any evidence of rejection or GVHD. When intestine from Lewis X Brown Norway hybrid rats (LBN) was transplanted into LEW rats, rejection occurred between day 6 and 9 and the time of onset of rejection was not influenced either by the length of transplanted bowel (10 to 80 cm, n = 6 each) or by whether the graft was from the jejunum or the ileum. However, rates of survival for 100 days from rejection were significantly better if 10 cm (100%) or 20 cm (84%) was transplanted than if the grafts were 40 cm or more in length (56%). The LBN recipients of LEW allografts developed GVHD on days 7 through 9, and this response was similarly unrelated to the length or segment of bowel transplanted. However, host survival was quite dependent on graft segment length and site of origin. All animals who received 20 cm or less of proximal bowel survived (with GVHD but no evidence of rejection). While 50% of the animals that received proximal intestinal grafts 40 cm in length survived GVHD, none who received identical-sized grafts from the distal ileum survived (all were dead by day 20). Our data document that the results of small-intestine transplantation is dependent on the length and site of origin of the grafts.     

Graft-versus-host disease in fully allogeneic small bowel transplantation in the rat

Small bowel and its mesentery contain considerable amounts of lymphoid tissue that can mediate graft-versus-host disease in small bowel transplant (SBT) recipients. Present studies determined the existence of GVHD in a fully allogeneic SBT model and examined the effect of donor pretreatment with ALS in eliminating GVHD. Adult male Lewis (Lew) rats received orthotopic small bowel transplants from untreated (LewxBN)F1 (LBNF1) donors (group 1) or Brown Norway (BN) donors that were untreated (group 2) or pretreated with ALS (days -2 and -1) (group 3). All recipients were treated with cyclosporine 15 mg/kg/day i.m. on days 0-6 postoperatively. Animals were weighed and examined daily for signs of rejection and GVHD. No animals in groups 1 or 3 showed any physical signs of GVHD, but all of those in group 2 had characteristic weight loss, diarrhea, and dermatitis between 4 and 6 weeks postoperatively, from which they all recovered. Histologic examination of skin and spleen at this time confirmed the presence of GVHD. The relative spleen weight [( spleen weight/body weight] x 100) of group 2 animals was also significantly greater than that of unoperated control Lew animals. Spleen cells obtained from group 2 animals at the time of subclinical GVHD, but not cells from group 1 or 3 animals, caused enlargement of popliteal lymph nodes when they were injected into the footpads of Lew rats. This study shows that GVHD can manifest itself in recipients of a fully allogeneic small bowel transplant even when rejection is prevented by effective immunosuppression with CsA. However, combined use of recipient treatment with CsA and pretreatment of donor animals with ALS eliminates all manifestations of GVHD.     

Characterization of immune responses in different lymphoid compartments during small intestinal allograft rejection

In the present study, we examined the sequential changes of procoagulant activity (PCA) in different host and graft tissue compartments in order to assess its role as an immunologic effector and monitor of the rejection process. An early increase in PCA in the graft mesenteric nodes marks the onset of the host-graft immune interaction prior to any PCA or histologic changes in the other tissue compartments. This was followed by increases in PCA in the peripheral blood and graft intraepithelial compartments coinciding with maximal clinical and histologic signs of rejection. Cyclosporin A fully suppressed alloantigen-induced activation of PCA in the intraepithelial compartment and peripheral blood mononuclear cells, but only partially suppressed PCA in graft mesenteric nodes of the allogeneic transplants. The sequence of PCA changes accurately reflected the clinical and histologic changes during allograft rejection. Thus, PCA measured in peripheral blood mononuclear cells appears to be a sensitive and accurate marker of allograft rejection.     

Donor and recipient pretransplant conditioning with nonlethal radiation and antilymphocyte serum improves the graft survival in a rat small bowel transplant model

BACKGROUND: Lymphoid tissue within the intestinal graft require immunomodulatory strategies to prevent graft versus host disease (GVHD) after transplant. Herein, we evaluate the potential advantage of donor-specific bone marrow infusions in donor and or recipient preconditioned with total body irradiation and or antilymphocyte serum (ALS) on the incidence of GVHD and rejection after small bowel transplantation. METHODS: Heterotopic SBTx was performed from DA to Lewis rats and distributed in nine groups: control group G0 (n=4) and G1 (n=6) without irradiation; recipients in G2 (n=4) were given 400 rd although in groups 3 (n=5), G4 (n=6), G6 (n=5), G7 (n=5), and G8 (n=6) with 250 rd. Donors in G5 (n=4) and G6 were given 250 rd of total body irradiation 2 hours before intestinal retrieval. Donors and recipients in G7 and donors in G8 additionally received ALS (day -5). G1, 2, 3, 5, 6, 7, and 8 were infused with UDBM and G4 with the same amount of TCDBM. Animals received tacrolimus for 15 days and accessed for rejection, GVHD and for chimerism analysis. RESULTS: High mortality due to GVHD was observed in G2, 3, and 4, and correlated with high levels of donor T cells in recipients blood. G0 and G1 showed early acute rejection with progression toward chronic rejection, in contrast to the preconditioned groups. High and low doses of total body irradiation resulted in allogeneic and in a mixed chimerism, respectively. Decrease in donor chimeric cells after 11 weeks in preconditioned groups was correlated with severe allograft rejection. CONCLUSION: Donor preconditioning with 250 rd and or ALS combined with recipient preconditioning and donor-specific bone marrow infusions prevented GVHD and resulted in a transient mixed chimerism with inhibition of allograft rejection after small bowel transplantation.     

Small intestine transplantation in the rat--immunology and function

Heterotopic, vascularized small intestine transplants were performed in inbred strains of rats to investigate the structural, functional, and immunologic consequences of intestinal transplantation with and without immunosuppression with cyclosporine (CyA). Lewis X Brown Norway F1 intestine was rejected by untreated Lewis recipients in 7 to 10 days. Structurally, rejected intestine was characterized by shortened crypts and villi lined by damaged attenuated epithelial cells. Functionally, rejection was associated with impaired epithelial active ion transport as indicated by decreased potential difference and with diminished epithelial barrier function as reflected by decreased transepithelial resistance. Administration of CyA for 7 days prevented clinical rejection and partially prevented the structural and functional defects. Lewis intestine transplanted into Lewis X Brown Norway F1 recipients caused fatal graft versus host disease (GVHD) in 9 to 17 days. Treatment with CyA for 7 days failed to prevent GVHD routinely, but prolonged administration delayed fatal GVHD until CyA was discontinued. Intestine from Lewis "B" rats made deficient of T cells by thymectomy, irradiation, and reconstitution with syngeneic T cell-depleted bone marrow failed to cause GVHD in Lewis recipients. Reconstitution of the "B" rats with T cells before transplantation restored the GVHD response. These results may be relevant in the consideration of clinical small intestinal transplantation.     

Immunologic consequences of combined pancreas-spleen transplantation in the rat

A rat model of combined pancreas-spleen transplantation (PST) was used in order to characterize the immunologic consequences of PST when compared to pancreas transplantation (PT) alone. Weakly MHC disparate Fischer (F344) PST grafts survived significantly longer in LEW recipients than did F344 PT grafts (17.6 +/- 3.4 vs 12.1 +/- 1.0 days, respectively, P less than 0.001). However, graft versus host disease (GVHD) occurred regularly in the PST recipients. Similarly, in haploidentical LBN to LEW donor-recipient pairs, PST graft survival was also modestly but significantly increased over that of the PT controls (10.6 +/- 1.0 vs 8.5 +/- 0.8 days, respectively, P less than 0.001). Conversely, in the ACI to LEW combination where MCH differences are very strong, PST graft survival was not longer than PT controls (7.5 +/- 0.8 vs 7.0 +/- 0.6 days, respectively, P greater than 0.2). GVHD was not observed in either of the latter two experiments. Short-term immunosuppression with cyclosporine further improved the outcome in LEW recipients of F344 grafts by inducing long-term graft survivals in approximately one-fourth of the PST recipients. Host splenectomy did not improve graft survival in PST recipients but did increase the risk of GVHD in LEW recipients of F344 PST grafts. Graft irradiation prior to transplantation with 500 rad not only abrogated the GVHD potential of the F344 PST graft but also eliminated the graft survival prolonging effect of the donor spleen. Donor spleen cells injected at the time of PT in F344 to LEW transplants resulted in graft prolongation not different from spleen intact PST recipients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transplantation of the spleen: effect of splenic allograft in human multivisceral transplantation

OBJECTIVES: To describe the effect of the splenic allograft in human multivisceral transplantation. SUMMARY BACKGROUND DATA: We performed transplants of the spleen as part of a multivisceral graft in an attempt to decrease both the risk of infection from an asplenic state and the risk of rejection by a possible tolerogenic effect. To our knowledge, this is the first report of human splenic transplantation in a large series. METHODS: All primary multivisceral recipients who received a donor spleen (N = 60) were compared with those who did not receive a spleen (N = 81). RESULTS: Thirty-five of 60 (58%) are alive in the spleen group, and 39 of 81 (48%) are alive in control group (P = 0.98). In univariate analysis, splenic recipients showed superiority in freedom-from-any rejection (P = 0.02) and freedom-from-moderate or severe rejection (P = 0.007). No significant differences were observed in analyses of infectious complications between the spleen and control groups. Both platelet and leukocyte counts became normal in splenic patients, whereas these counts were significantly increased in nonsplenic recipients. Observed incidence of graft versus host disease (GVHD) was 8.25% (5 of 60) in the spleen group and 6.2% (5 of 81) in the control group (P = 0.70). Increased incidence of autoimmune hemolysis was observed in the spleen group. CONCLUSIONS: Allograft spleen can be transplanted within a multivisceral graft without significantly increasing the risk of GVHD. The allogenic spleen seems to show a protective effect on small bowel rejection. Further investigation with longitudinal follow-up is required to precisely determine the immunologic and hematologic effects of the allograft spleen.     

Incidence of graft rejection in small bowel transplanted pigs after immunosuppression withdrawal

As intestinal grafts require heavy immunosuppression, there are no reports of immunosuppression withdrawal after clinical small bowel transplantation. In this large-animal study, we investigated the occurrence of graft rejection in intestinal-transplanted pigs after withdrawal. Large-White unrelated piglets were transplanted and divided in three groups: group 1 (n = 5), intestinal transplantation (ITx) with no immunosuppression; group 2 (n = 7), Itx and 60 days of treatment with tacrolimus and mycophenolate mofetil; group 3 (n = 5), Itx and donor bone marrow infusion (DBMi) and 60 days of treatment with tacrolimus and mycophenolate mofetil. Follow-up time after withdrawal was 120 days. Group 1 pigs died of graft acute cellular rejection (ACR) after a median of 11 days. In group 2, two pigs died of ACR-related infection and another two of ACR within 90 days. The remaining three animals (43%) were sacrificed at day 180, and their grafts showed no signs of ACR. In group 3, two pigs died of ACR-related infection and one of graft versus host disease within 80 days; at day 180 the two surviving animals showed signs of chronic rejection in the allograft. This study demonstrates that total withdrawal after ITx is followed by sudden and lethal ACR (or ACR-related infection) in more than 50% of the recipients. When a tolerance-inducing strategy as DBMi is applied, lethal graft versus host disease may also occur. In group 3, the intestinal allograft, to which the recipients were partially tolerant, developed chronic rejection that was probably associated with a decline with time of donor-leukocytes chimerism, as recently demonstrated in rats.     

Graft irradiation abrogates graft-versus-host disease in combined pancreas-spleen transplantation

A model of combined pancreas-spleen transplantation (PST) was studied in LBN F1 recipients of Lewis grafts in order to evaluate the efficacy of pretransplant graft irradiation in preventing lethal graft-versus-host disease (GVHD). Recipients of unmodified PST uniformly developed severe GVHD and died (MST = 16.7 +/- 3.8 days). Whole body donor irradiation with either 500 or 250 rad prevented lethal GVHD. Similarly, ex vivo graft irradiation with either 1000 or 500 rad also resulted in normal weight gain, graft function, and host survival for the 6-week study period. Conversely, delay of graft irradiation until 3 days after transplantation failed to prevent this complication (MST = 15.8 +/- 3.7 days). Recipients of irradiated grafts displayed glucose tolerance tests that were identical to those in the control group indicating that the doses of radiation employed in these experiments were not deleterious to islet function. Irradiated spleen grafts appeared histologically normal at 6 weeks after transplantation. Cells derived from these grafts failed to stimulate lymph node enlargement in a popliteal lymph node assay for GVHD, suggesting that these spleens may have become repopulated with host cells. These experiments confirm that PST has the potential to cause lethal GVHD and suggest that pretransplant graft irradiation may be used to prevent its occurrence.     

Host-graft relationship: the systemic nature of allograft rejection

The interdependence between immunologic events occurring within acutely rejecting rat cardiac allografts and those in host lymphoid tissues were studied. To evaluate cellular dynamics of allograft infiltration, 111In-labeled thoracic duct lymphocytes from Lewis rats were administered intravenously daily (0 to 7 days after transplantation) to (Lewis X BN)F1 heart-grafted unmodified Lewis rats, sacrificed 24 hours later. Accumulation of thoracic duct lymphocytes in the allografts peaked 4 to 5 days after transplantation. To evaluate whether these changes at the graft site were sufficient to carry on the rejection response in the absence of a sustained host immunologic drive, acutely rejecting (Lewis X BN)F1 cardiac allografts were retransplanted serially at days 1 through 5 into normal syngeneic animals. All these regrafts survived greater than 100 days. Neither infusion of interleukin-2-conditioned medium (100 IU for 7 days intravenously) into regrafted hosts nor preoperative perfusion of the retransplanted hearts with interleukin-2-conditioned medium (300 IU) could complete the rejection process. Using flow cytometry analysis, we then assessed the phenotypic alterations of the mononuclear cells infiltrating the graft. The ratio of T helper: T cytotoxic/suppressor cells, which at day 3 was 1.57, inverted abruptly to 0.67 by days 5 to 6. After retransplantation a dramatic depression in T-lymphocyte subsets occurred, particularly affecting the T cytotoxic/suppressor phenotype. Trafficking studies revealed that the T cells that left the regrafts migrated mainly to spleen and mesenteric lymph nodes and away from bone marrow and peripheral blood of the syngeneic secondary recipients. Finally, histologic manifestations of acute rejection at days 4 to 5 virtually reversed themselves after regrafting. These studies emphasize the systemic nature of the rejection cascade, which depends fully on the host lymphoid system; even late changes in the graft microenvironment are not sufficient to produce final immunologic destruction.     

A study of tolerance induced by liver transplantation on intestinal graft in the rat]

In some strain combinations of rats, orthotopic liver transplantation (OLT) permits long-term donor-specific survival of fully allogeneic kidney, heart or skin grafts. The difficulties encountered in the clinical situation to obtain tolerance of small-bowel transplantation (SBT), in spite of massive non-specific immunosuppression, led us to study possible liver-induced tolerance in SBT. Inbred DA (RTIa) and PVG (RT1c) rats were used respectively as donors and recipients and divided in two groups: group 1: SIT alone (n = 6); group 2: combined OLT/SBT (n = 6). SIT was performed 17 days after OLT. No immunosuppressive treatment was given to the recipients. Biopsies of small-bowel grafts were performed in both groups at various times after small bowel engraftment. All animals in group 1 showed evidence of acute rejection of the graft between days 6 and 9 post-graft. The histologic pattern of rejection associated lamina propria (LP) mononuclear cell infiltration, crypt lesions and villous atrophy at the end-point of rejection. In group 2, long-term survival (> 100 days) of small bowel grafts was achieved in five of the six animals in spite of strong mononuclear cell infiltration in the LP, which peaked two months after small bowel grafting but then disappeared partially. This striking mononuclear cell infiltrate contrasted with only minor epithelial damage. These data demonstrate that liver grafting can enhance the survival of a small-bowel graft from the same donor in a rat model. Histological findings show that an intense immunological reaction takes place within liver-induced tolerated small-bowel grafts.     

Facial tissue allograft transplantation

A hemifacial allograft transplant model was used to investigate the rationale for development of functional tolerance across an MHC barrier. Thirty hemiface transplantations were performed in five groups of six Lewis (RT1(1)) rat recipients each. Isografts were performed in group 1. Transplants were obtained from semiallogenic LBN(RT1(1+n)) in group 2 and from fully allogenic ACI(RT1(a)) in group 3 donors, which served as allograft rejection controls. Group 4 grafts using LBN donors and group 5 using ACI donors in addition received CsA monotherapy (16 mg/kg/d for 1 week) and maintained at 2 mg/kg/d. Signs of graft rejection were sought daily. Isograft controls survived indefinitely. All nontreated allografts were rejected within 5 to 8 days posttransplant. Eighty-three percent of face-transplant recipients from LBN donors and 67% from ACI donors did not show any signs of rejection up to 270 days and 200 days, respectively. Flow cytometry at day 63 in LBN recipients showed the presence of donor-specific chimerism for MHC class I RT1(n) antigens, namely 3.39% CD4/RT1(n); 1.01% CD8/RT1(n) T-lymphocytes; and 3.54% CD45RA/RT1(n) B-lymphocytes. In ACI recipients the chimerism test revealed 10.55% CD4/RT1(a) and 4.59% of CD8/RT1(a) T-lymphocytes. MLR assay at day 160 posttransplant revealed suppressed responses against LBN donor antigens in group 4, but moderate reactivity to ACI donor antigens in group 5. Functional tolerance toward hemifacial allograft transplants induced across MHC barrier using a CsA monotherapy protocol was associated with the presence of donor-specific chimerism in T- and B-cell subpopulations.     

FTY720介导淋巴细胞凋亡抑制小肠移植的移植物抗宿主免疫反应

目的 探讨免疫调节药物FTY720对小肠移植后急性移植物抗宿主病（GVHD）的治疗效果及其作用机制.方法 应用Wistar-Furth（WF）大鼠作为供体,WF和ACI大鼠的子代（F1）作为受体,同种异基因异位全小肠移植的技术方法建立GVHD的动物模型.移植受体分为实验组和对照组,每组6只.实验组从移植手术当日开始予以FTY720治疗,持续14 d;对照组在相同的时间段口服蒸馏水.术后第15天,提取受体靶器官肝脏、小肠及移植物小肠的淋巴细胞,应用免疫组织化学（免疫组化）TUNEL法和流式细胞仪检测两组淋巴细胞凋亡的变化.结果 对照组大鼠术后均死亡于GVHD,平均生存时间（16.0±1.7）d,实验组大鼠均长期成活超过100 d,两组差异具有统计学意义（P＜0.01）.免疫组化TUNEL法检测结果显示,实验组肝脏和移植物小肠黏膜的淋巴细胞凋亡比率均明显高于对照组,差异具有统计学意义（P＜0.05）.流式细胞技术分析结果显示,实验组大鼠移植物小肠黏膜内凋亡的淋巴细胞百分比为19.4%,明显高于对照组的11.8%（P＜0.05）;而肝脏凋亡的淋巴细胞百分比两组差异无统计学意义（P＞0.05）.结论 FTY720可能通过诱导淋巴细胞的凋亡,减少和抑制GVHD对靶器官的损害,改善移植大鼠的预后.     

Experimental short-term immunosuppression after bowel transplantation and donor-specific bone marrow infusion.

HYPOTHESIS: We previously showed in a large animal pig model that unmodified donor-specific bone marrow infusion (DSBMI) did not facilitate total bowel engraftment; in contrast, it increased the risks of rejection, infection, and graft-vs-host disease (GVHD) posttransplant. We hypothesize that continuous immunosuppression, in combination with DSBMI, might contribute to-or even trigger-these unwarranted immune responses by both host and graft; therefore, discontinuing immunosuppression might decrease these risks and prolong survival. METHODS: Six groups of outbred, mixed lymphocyte culture-reactive pigs underwent a total (small and large) bowel transplant: group 1, nonimmunosuppressed control pigs (n = 5); group 2, nonimmunosuppressed DSBMI pigs (n = 6); group 3, tacrolimus (indefinite) pigs (n = 7); group 4, tacrolimus (indefinite) plus DSBMI pigs (n = 7); group 5, tacrolimus (10 days only) pigs (n = 5); and group 6, tacrolimus (10 days only) plus DSBMI pigs (n = 6). RESULTS: The combination of short-term immunosuppression and DSBMI (group 6) significantly prolonged survival, compared with short-term immunosuppression only (group 5) or DSBMI only (group 2). Short-term immunosuppression and DSBMI (group 6) did not prolong overall survival, compared with indefinite immunosuppression with (group 4) or without (group 3) DSBMI: survival rates at 7, 14, and 28 days posttransplant were 100%, 100%, and 67% in group 6; 100%, 100%, and 71% in group 3; and 100%, 67%, and 47% in group 4 (P =.14). Short-term immunosuppression and DSBMI (group 6) increased the incidence of rejection, infection, and GVHD, compared with indefinite immunosuppression without (but not with) DSBMI. CONCLUSIONS: Short-term immunosuppression and DSBMI did not prolong survival and did not reduce the incidence of death from rejection, infection, or GVHD, compared with indefinite immunosuppression without DSBMI. But short-term immunosuppression and DSBMI resulted in a lower incidence of death from infection and GVHD, compared with indefinite immunosuppression and DSBMI. When immunosuppression was discontinued 10 days posttransplant, the effect of DSBMI was insufficient to avert death from rejection. CLINICAL RELEVANCE: The clinical results of bowel transplantation trail those of other solid organ transplants. It reduced the rates of infection and GVHD. Our study shows that systemically infused donor-specific bone marrow with short-term or indefinite immunosuppression does not improve outcome after bowel transplantation. It seems necessary to modify the time, dosing, routing, and/or composition of donor-specific bone marrow before it can be successfully used in clinical bowel transplantation.     

The role of tumor necrosis factor in allograft rejection. III. Evidence that anti-TNF antibody therapy prolongs allograft survival in rats with acute rejection

We have previously demonstrated that TNF-alpha levels are elevated in liver transplant patients experiencing acute rejection. In addition, prophylactic administration of anti-TNF-alpha or anti-TNF-beta antibodies prolonged graft survival in a rat heterotopic cardiac transplant model. This experiment was designed to evaluate anti-TNF therapy in the treatment of acute allograft rejection. Heterotopic cardiac transplants were performed using Buffalo donors and Lewis recipients. Histologic sections of transplanted grafts from untreated animals revealed significant rejection at day 4 with terminal rejection occurring on day 10.8 +/- 0.4. Animals in the experimental groups received antirejection therapy from postoperative days 4-13. Treatment with cyclosporine at 2 mg/kg/day prolonged graft survival to 16.5 +/- 2.0 days (P = 0.01 versus controls). Administration of polyclonal anti-TNF-alpha in combination with polyclonal anti-TNF-beta increased graft survival to 14.6 +/- 0.4 days (P less than 0.001 versus controls). Use of a monoclonal anti-TNF-alpha antibody was even more effective, with graft survival of 17.4 +/- 0.7 days (P less than 0.001 versus controls). Combination immunotherapy with monoclonal anti-TNF-alpha in conjunction with CsA extended survival to greater than 30 days. In contrast, recombinant TNF-alpha (5 micrograms/day, i.p.) markedly accelerated the time to graft failure (7.4 +/- 0.2 days, P less than 0.001 versus controls). Examination of explanted graft tissue on postoperative day 9 from animals treated with anti-TNF showed decreased mononuclear cell infiltrate when compared to untreated animals. Treatment with TNF-alpha markedly increased the inflammatory process. These results suggest that TNF may play a role in the pathogenesis of acute rejection.     

Monocyte/macrophage procoagulant activity as a measure of immune responsiveness in Lewis and brown Norway inbred rats. Discordance with lymphocyte proliferative assays

In vitro lymphocyte proliferative assays were performed using Lewis (Lew) and Brown Norway (BN) rats, and compared to induction of monocyte/macrophage procoagulant activity (PCA) in a mixed lymphocyte culture and by endotoxin (LPS) (E. Coli 0111:B4). Splenic mononuclear cells from Lew rats had significantly greater mitogen-induced proliferation to concanavalin A (P = .002) and phytohemagglutinin (P = 0.007). The Lew cells also showed greater allogeneically induced proliferation by BN cells in a one-way MLC in comparison to the reciprocal BN proliferative response (P less than 0.04). PCA induction in peripheral blood mononuclear cells (PBM) by allogeneic stimulation in MLC or total content PCA by LPS did not vary significantly between the 2 strains (P greater than 0.5). Induction of PCA by LPS was rapid, with a moderate rise over basal activity at 3 hr and maximal activity at 6 hr. Two-way allogeneic induction of PCA in PBM from BN and Lew rats resulted in PCA elevation by 3 hr, which became maximal at 18 hr. One-way MLC with Lew or BN cells as responders resulted in moderate increases in PCA by 3-6 hr, with equivalent maximal activities recorded at 18 hr. Viable PCA accounted for 26-32% of total content PCA in both Lew and BN rats. Maximal allogeneic PCA induction by MLC was 14-18% of PCA induced by LPS and required a longer incubation for its expression. Our results indicate that in vitro PCA expression by Lew and BN PBM following allogeneic or endotoxin stimulation shows little interstrain variability in comparison to lymphocyte proliferative responses. Thus PCA appears to more closely reflect the observed in vivo responses of these strains to allogeneic challenge.     

异种移植组织相容性及免疫动态变化测试模型

目的　综述异种移植物抗宿主反应 (GVHD)动物模型的研究现状、检测方法及进展情况。方法　采用文献回顾与综合分析方法。结果　免疫活性细胞植入异种受者体内后 ,有发生排斥 (HVGD)、移植物抗宿主反应(GVHD)和微嵌合的可能 ,异种 GVHD已在小动物和大动物体内成功诱导 ,并可通过多种途径进行检测。结论　异种GVHD大动物模型 ,主导因素是嵌合细胞 ,利用该模型可真实模拟异种移植免疫细胞动态变化过程     

51Cr-EDTA: a marker of early intestinal rejection in the rat

Intestinal permeability was studied after accessory intestinal transplantation in Lewis rats. Five groups were evaluated: Group 1--isografts (N = 6); Group 2--Lewis X Brown Norway F1 (LBN-F1) allografts (N = 6); Group 3--isografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 4--LBN-F1 allografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 5--LBN-F1 allografts treated with CsA 4 mg/kg/day X 28 days (N = 6). Chromium-labeled ethylenedimianetetraacetate (51Cr-EDTA) was given through the proximal stoma of the graft. Renal clearance of 51Cr-EDTA and mucosal biopsies were followed post-transplant. The biopsies of the intestinal graft showed no rejection in Groups 1, 3, and 5; fulminant rejection in Group 2; and mild atypical rejection in Group 4. 51Cr-EDTA clearance was elevated in all groups during the first 7 days post-transplant. Thereafter, 51Cr-EDTA excretion fell to lower levels in the animals with histologically normal grafts (Groups 1, 3, and 5). 51Cr-EDTA excretion in Group 4 was increased with the first histological evidence of rejection on Day 14 and remained elevated until sacrifice (P less than 0.02 compared to Groups 3 and 5). A transient permeability defect occurs after intestinal grafting. Once the graft has recovered from this injury, 51Cr-EDTA is a sensitive marker for intestinal rejection.     

Graft versus host disease in small bowel transplantation

Quantities of organized lymphoid tissue in small bowel allografts may cause graft versus host disease (GVHD) following transplantation. This study examines the effect of graft mesenteric lymphadenectomy on development of GVHD following small bowel transplantation in rats. GVH reactivity was assessed by measuring the degree of graft cell emigration to the host. In the PVG to DA strain combination, graft mesenteric lymphadenectomy led to a significant reduction in graft cell colonization of host lymphoid tissues from 40-50 per cent to 25-35 per cent. Transplantation from PVG to (PVG x DA)F1 hybrids caused fatal GVHD within 21 days whereas when DA donors were used survival was over 30 days. When mesenteric lymphadenectomy was performed on PVG donors, host survival increased by only 3-4 days. Mesenteric lymphadenectomy in DA donors led to long-term recipient survival with no GVHD. Intensity of GVHD following rat small bowel transplantation is a strain-dependent phenomenon and graft mesenteric lymphadenectomy does not always prevent GVHD. The mucosa may have an important immunological role.     

The use of FK-506 for small intestine allotransplantation. Inhibition of acute rejection and prevention of fatal graft-versus-host disease.

Small intestine allotransplantation in humans is not yet feasible due to the failure of the current methods of immunosuppression. FK-506, a powerful new immunosuppressive agent that is synergistic with cyclosporine, allows long-term survival of recipients of cardiac, renal, and hepatic allografts. This study compares the effects of FK-506 and cyclosporine on host survival, graft rejection, and graft-versus-host-disease in a rat small intestine transplantation model. Transplants between strongly histoincompatible ACI and Lewis (LEW) strain rats, and their F1 progeny are performed so that graft rejection alone is genetically permitted (F1----LEW) or GVHD alone permitted (LEW----F1) or that both immunologic processes are allowed to occur simultaneously (ACI----LEW). Specific doses of FK-506 result in prolonged graft and host survival in all genetic combinations tested. Furthermore, graft rejection is prevented (ACI----LEW model) or inhibited (rejection only model) and lethal acute GVHD is eliminated. Even at very high doses, cyclosporine did not prevent graft rejection or lethal GVHD, nor did it allow long-term survival of the intestinal graft or the host. Animals receiving low doses of cyclosporine have outcomes similar to the untreated control groups. No toxicity specific to FK-506 is noted, but earlier studies by other investigators suggest otherwise.