Genetic deletion of chemokine receptor CXCR3 or antibody blockade of its ligand IP-10 modulates posttransplantation graft-site lymphocytic infiltrates and prolongs functional graft survival in pancreatic islet allograft recipients

BACKGROUND: Interaction of chemokine receptor CXCR3 with its ligand IP-10 mediates effector cell trafficking to sites of allograft rejection in murine models of whole organ allotransplantation. We hypothesized that blocking the CXCR3/IP-10 interaction would impair posttransplantation leukocyte trafficking to and delay rejection of pancreatic islet allografts. METHODS: A/J strain murine islets were implanted to the kidney capsule of H-2 disparate, streptozotocin-induced diabetic wild type (WT), CXCR3 deficient (CXCR3(-/-)) or IP-10 antibody-treated WT (alphaIP-10) C57BL/6 recipients. Representative grafts from each group were harvested at day 7. Ribonuclease protection assay was used to determine gene expression for cell markers F4/80 (macrophages), CD8 (type I T cells), CD4 (type II T cells), and CD 19 (natural killer cells), and for chemokines IP-10, MIP-1alpha, MIP-1beta, MCP-1, and RANTES. Immunohistochemistry was used to confirm ribonuclease protection assay infiltrate data. Graft-site chemokine gene expression and cellular infiltrate were correlated with time to functional graft rejection. RESULTS: Untreated WT recipients demonstrated heavy graft-site cell infiltrates and increased graft-site gene expression for cell markers F4/80, CD8, CD4, and CD19, and for chemokines RANTES, IP-10, and MIP-1beta at day 7. In comparison with untreated WT, alphaIP-10-treated WT and CXCR3(-/-) recipients demonstrated the same degree of chemokine gene expression but less lymphocytic infiltrate. The mean length of allograft survival was 12.7 +/- 3.1 days in untreated WT versus 20.2 +/- 2.7 days (P <.05) for CXCR3(-/-)- and 19.7 +/- 2.3 days (P <.05) for alphaIP-10-treated WT recipients. CONCLUSIONS: CXCR3 gene deletion or alphaIP-10 antibody therapy modulates posttransplantation lymphocytic graft infiltration and statistically prolongs graft survival in murine islet allograft recipients.     

Splenectomy and renal allograft survival in the rat

The effect of splenectomy on renal allograft survival is not clear. In the rat, spleens isolated from recipients with functioning grafts have been shown to be a major source of cells that are capable of suppressing the rejection response (suppressor T lymphocytes). Thus the removal of the spleen in these allograft recipients could be detrimental to renal allograft survival. This study investigates this hypothesis, and looks for the presence of suppressor cells in other lymphoid organs apart from the spleen. In the rat renal allograft model, donor Lewis spleen cells given to DA recipients intravenously 1 week before transplantation of a Lewis kidney leads to indefinite allograft survival (median survival time (MST) greater than 100 days). Splenectomy before or after pretreatment with donor spleen cells failed to abrogate this effect (MST greater than 100 days). Experiments were performed in which cells or serum were prepared from long-term surviving splenectomized animals which had already been pretreated and transplanted, and then were injected into untreated recipients (adoptive transfer experiments). This was done to determine if cells capable of suppressing graft rejection were present in lymphoid organs outside the spleen in these splenectomized recipients. Thus the IV transfer of 10(8) lymph node cells harvested from splenectomized DA recipients with a long-term surviving LEW graft (LTS), into untreated but lightly irradiated (200 rad) DA recipients resulted in indefinite survival of a fresh Lewis kidney (MST greater than 100 days). In contrast, adoptive transfer of normal DA lymph node cells was ineffective (MST 13 days). Thus splenectomy is not necessarily detrimental to graft survival, as cells capable of preventing graft rejection are found in other lymphoid organs, such as lymph nodes, in splenectomized recipients.     

Organ-specific differences in the function of MCP-1 and CXCR3 during cardiac and skin allograft rejection

BACKGROUND: Chemokines are well-established to function in the recruitment of leukocytes into allografts in the course of rejection. Moreover, some studies have indicated that there are organ-specific differences in chemokine function, but the mechanism accounting for this difference is not known. METHODS: Fully major histocompatibility complex-mismatched vascularized cardiac transplants or skin transplants were performed using BALB/c (H-2d), C57BL/6 (H-2b), MCP-1-/- (H-2b) and CXCR3-/- (H-2b) mice as donors or recipients. Also, skin grafts (H-2b) were placed onto SCID mice (H-2d) that received BALB/c splenocytes (H-2d) by adoptive transfer either at the time of transplantation, or after a period of 28 days. RESULTS: Cardiac allografts in MCP-1-/- recipients survived significantly longer (P<0.0005) than wild-type (WT) controls. However, there was no prolongation of survival when MCP-1-/- grafts were used a donors in WT mice. In contrast, the absence of donor but not recipient MCP-1 prolonged skin allograft survival. WT donor cardiac grafts in CXCR3-/- recipients had a modest prolongation of survival (P<0.0005), whereas CXCR3-/- donor cardiac grafts in WT recipients were rejected similar to controls. Also, while recipient CXCR3 had no effect on the rejection of skin, CXCR3-/- donor skin grafts survived significantly longer than WT controls. This survival advantage was lost when vascularized CXCR3-/- skin grafts were used as donors in the SCID model of rejection. CONCLUSION: Recipient derived MCP-1 and CXCR3 are functional in the rejection of vascularized, but not nonvascularized, allografts. In contrast, donor-derived MCP-1 and CXCR3 are functional in nonvascularized, but not vascularized grafts.     

Differential expression of chemokines and chemokine receptors in murine islet allografts: the role of CCR2 and CCR5 signaling pathways

Chemokines and their receptors play a pivotal role in the initiation and amplification of the immune response. Investigated was their differential expression after syngeneic and allogeneic islet transplantation. During the 7 d after transplantation, the chemokines MCP-1, MCP-2, RANTES, MIG, IP-10, I-TAC, and two CC chemokine receptors CCR2 and CCR5 were highly expressed in allografts when compared with isografts. Disrupting the CCR2 and CCR5 pathways individually resulted in prolongation of the survival time 16.1 +/- 0.4 and 15.8 +/- 0.9 d, respectively, of fully major histocompatibility complex-mismatched islet grafts compared with wild-type controls (11.2 +/- 1.0 d). Blockade of both receptors had no synergistic effect. Rapamycin-treated wild-type recipients rejected their grafts at 17.4 +/- 2.2 d, in contrast to rapamycin-treated CCR2-/- recipients at 38 +/- 8.6 d (P = 0.025). The disruption of the CCR2 and CCR5 signaling, alone or in combination, moderately prolong islet allograft survival. However, the combination of low-dose immunosuppression and targeting of CCR2 greatly augmented islet graft survival.     

Beta7 integrins contribute to skin graft rejection

BACKGROUND: Because integrins alpha4beta7 and alphaEbeta7 contribute to epidermotropism of T-cells during skin inflammation, we sought to study their role in skin allograft rejection. METHODS: Wild-type (WT) (beta7+/+) and beta7 gene knockout (beta7-/-) C57BL/6 (H-2(b)) mice and SJL/J (H-2(s)) mice served as donors and recipients of allogeneic skin grafts. An anti-integrin beta7 subunit mAb (FIB504.64) was used to treat WT beta7+/+ C57BL/6 recipients of skin grafts from SJL/J mice. RESULTS: WT C57BL/6 recipients acutely rejected skin from SJL/J mice in 13 days. In contrast, the survival of SJL/J skin on either beta7-/- gene knockout or WT C57BL/6 recipients treated with anti-beta7 subunit mAb, was prolonged by 6 to 7 additional days (P<0.01). The survival of skin allografts from either beta7-/- or beta7+/+ C57BL/6 mice received by SJL/J recipients was not prolonged (P >0.05). CONCLUSIONS: Beta7 integrins contribute to skin graft rejection, in accord with their role in mediating the epidermotropism of T-cells during skin inflammation.     

Characterization of donor dendritic cells and enhancement of dendritic cell efflux with CC-chemokine ligand 21: a novel strategy to prolong islet allograft survival

Dendritic cells (DCs) are the most potent antigen-presenting cells, yet little data are available on the differential characteristics of donor and recipient DCs (dDCs and rDCs, respectively) during the process of islet allograft rejection. DTR-GFP-DC mice provide a novel tool to monitor DC trafficking and characteristics during allograft rejection. We show rapid migration of dDCs to recipient lymphoid tissues as early as 3 h post-islet allotransplantation. Compared with rDCs, dDCs express different patterns of chemokine receptors, display differential proliferative capacity, and exhibit a higher level of maturity; these findings could be attributed to the effects of injury that dDCs undergo during islet cell preparation and engraftment. Intriguingly, we detected dDCs in the spleen of recipients long after rejection of islet allografts. Given that dDCs express high levels of CCR7, islets were cultured before transplant with the ligand for CCR7 (CCL21). This novel method, which enabled us to enhance the efflux of dDCs from islet preparations, resulted in a prolongation of islet allograft survival in immunocompetent recipients. This study introduces dDCs and rDCs as two distinct types of DCs and provides novel data with clinical implications to use chemokine-based DC-depleting strategies to prolong islet allograft survival.     

Tim-3在小鼠心脏移植受者体内不同部位T淋巴细胞上表达的变化

目的 检测激活的T_H1类淋巴细胞标记分子"T淋巴细胞免疫球蛋白域及粘蛋白域蛋白-3(Tim-3)"在受者体内不同部位T淋巴细胞上表达的变化,探讨其与急性排斥反应的关系.方法 建立小鼠同基因和异基因心脏移植模型(简称:同基因组和异基因组);移植术后第3和第6天,分离和制备两组受者外周血、脾脏、引流淋巴结和移植心内淋巴细胞悬液,采用流式细胞仪检测Tim-3阳性细胞在CD4~+ 和CD8~+ T淋细胞中的比值.结果 两组受者术后外周血和脾脏内Tim-3~+/CD4~+以及Tim-3~+/CD8~+ 的比值比较,差异均无统计学意义(P>O.05).与同基因组比较,异基因组引流淋巴结内Tim-3~+/CD4~+ 比值轻度升高(P<0.05);但异基因组术后第6天与第3天比较,差异无统计学意义(P>0.05).与同基因组比较,移植心内Tim-3~+/CD4~+和TiM-3~+/CD8~+比值均显著升高(P<0.01);异基因组术后第6天与第3天比较.移植心TiM-3~+/CD4~+和Tim-3~+/CD8~+比值也显著升高(P<0.01).结论 小鼠异基因心脏移植受者引流淋巴结和移植心内T淋巴细胞上Tim-3的表达升高与急性排斥反应的进展动态相关.     

Secondary Lymphoid Organs Are Important But Not Absolutely Required for Allograft Responses

The role of secondary lymphoid organs in adaptive immune responses following transplantation is controversial. To examine the requirement for peripheral lymphoid organs in mounting immune responses to transplantation antigens, lymphotoxin alpha-deficient (LTalpha-/-) and LTbeta-receptor-deficient (LTbetaR-/-) mice that lack lymph nodes and Peyer's patches were used as recipients of fully allogeneic heart and skin grafts. Splenectomized LTalpha-/- and LTbetaR-/- mice effectively rejected skin and cardiac allografts, although with delayed kinetics when compared with wild-type controls. In addition, initial skin allograft challenge in splenectomized LTbetaR-/- mice resulted in accelerated rejection of subsequent donor cardiac allografts when compared with heart rejection in nonsensitized controls. Thus, although peripheral lymphoid organs play an important role in allowing allograft responses to occur, they do not appear to be absolutely required for either acute allograft rejection, or T-cell priming. These results suggest that immunologic events capable of leading to allograft rejection can successfully occur at sites other than classical secondary lymphoid organs.     

Inducible nitric oxide synthase promotes cytokine expression in cardiac allografts but is not required for efficient rejection.

BACKGROUND: Inducible nitric oxide synthase (iNOS) is enhanced during acute rejection. Pharmacologic inhibition of nitric oxide synthase (NOS) activity has had variable effects on graft survival in a number of animal models. To further characterize the requirement and effects of iNOS during acute allograft rejection, we examined rejection responses of mice completely deficient of iNOS. METHODS: Heterotopic cardiac allografts were performed using wild-type and iNOS deficient mice (iNOS[-/-]) as recipients. Graft survival was determined by abdominal palpation. At days 3 and 7 following transplantation, grafts were harvested and analyzed histologically. Cytokine messenger RNA (mRNA) expression was measured by ribonuclease protection assay. RESULTS: Mean survival time of cardiac allografts did not differ between wild-type (18 +/- 3 days) and iNOS(-/-) recipients (16 +/- 2 days). At 3 days, findings of moderate acute rejection were seen in both recipients groups, although modestly reduced in iNOS(-/ -) mice. By 7 days, allografts in both groups demonstrated severe rejection. Within grafts at day 3, there was a 3-fold reduction in IL-1beta expression and a 4-fold reduction in IL-1RA in iNOS(-/-) recipients (p = 0.03 andp = 0.04, respectively) compared to wild-type recipients. Expression of other proinflammatory cytokines was detected in the grafts from both recipients, but was not significantly different. Finally, rejection responses to iNOS(-/-) cardiac allografts were nearly identical to wild-type allografts. CONCLUSIONS: Rejection of cardiac allografts by iNOS(-/-) mice occurs in a similar fashion to wild-type recipients, with extensive inflammation and proinflammatory cytokine production. While iNOS may play a role in cytokine induction by macrophages, these studies suggest that iNOS is not required for efficient cardiac graft rejection.     

Pretransplant sensitization with major histocompatibility complex class I+ class II- hepatocytes leads to accelerated skin graft rejection.

The immunogenicity of major histocompatibility complex (MHC) class I+ class II- hepatocytes is controversial. We studied the effect of pretransplant donor-specific sensitization with either purified hepatocytes (HC) or splenocytes (Spl) on subsequent skin allograft survival. Five million Percoll-purified DBA HC or 10 x 10(6) DBA Spl were injected into C57BL/6 recipients either intraperitoneally (ip) or into a sponge matrix allograft. Twelve days later, sensitized mice received a DBA skin graft. On the same day, allogeneic (DBA) and syngeneic (BL/6) skin grafts were placed on naive BL/6 mice. In naive BL/6 mice, allogeneic skin graft survival was 7.8 +/- 0.5 days (n = 4), and syngeneic survival was indefinite (n = 5). Skin graft survival (mean +/- SD in days) in recipients sensitized with hepatocytes ip was 6.0 +/- 1.2 days (n = 5) compared with 5.6 +/- 0.5 days in recipients sensitized with splenocytes ip. Similarly, graft survival in recipients that received hepatocytes into a sponge matrix allograft was 5.67 +/- 1 days (n = 6) compared with 5.2 +/- 1.1 days (n = 8) in those that received splenocytes into the sponge. There was no difference in graft survival between mice sensitized with HC vs Spl, nor between mice injected ip vs with the sponge. All sensitized mice experienced accelerated graft rejection compared with naive controls (P less than 0.000). These results demonstrate that purified MHC class I+, class II- murine HCs are immunogenic in vivo. Sensitization with donor-specific HCs led to accelerated rejection of subsequent skin grafts, similar to the accelerated rejection seen after sensitization with MHC class I+ and class II+ splenocytes.     

Immunosuppressive and trafficking properties of donor splenic and bone marrow dendritic cells

BACKGROUND: Infusion of donor dendritic cells (DC) has been shown to prolong allograft survival in a number of models. However, many regimens that utilize donor DC do not consistently produced tolerance or long-term allograft survival. We hypothesized that one factor limiting the therapeutic effect of donor DC is their relative inability to traffic to recipient peripheral lymph nodes and inhibit the function of resident alloreactive T cells. METHODS: Donor strain DC isolated from the spleens or bone marrow of Flt3L-treated mice were transferred intravenously into recipients at the time of skin grafting. Where indicated, recipients were treated with an anti-CD40L antibody and CTLA4-Ig. RESULTS: Infusion of donor DC together with costimulatory blockade promoted donor-specific prolongation of skin allograft survival in mice. Perhaps due to their more immature phenotype, bone marrow DC trafficked more effectively to the spleen, bone marrow, and thymus and were associated with significantly longer allograft survival than were splenic DC. Neither population of DC trafficked well to peripheral lymph nodes. Consistent with our hypothesis, splenic but not lymph node T cells from DC-treated recipients displayed donor-specific hyporesponsiveness in vitro. CONCLUSION: These data suggest that one factor contributing to rejection following treatment with donor DC plus costimulation blockade is the persistence of donor-reactive T cells within the recipient's secondary lymphoid structures. Strategies to improve DC trafficking to these structures may enhance their therapeutic effect.     

Prolonged survival of heart allografts from p53-deficient mice

BACKGROUND: Acute rejection of the heart allograft is the major cause of heart failure in the first month after transplantation. Most studies on the prevention of acute rejection have concentrated on immune suppression of the recipients, whereas little is known about the effects of genetically manipulated donor organs on heart allograft survival. Herein, we describe a mouse model of heart allografts donated by p53-/- mice that can prolong the survival time of the grafts. METHODS: Hearts of p53-/- or p53+/+ C57BL/6J mice were grafted to the neck carotid artery and jugular vein of BALB/c mice using a cuff technique. The graft survival was observed daily. The hearts were analyzed using several techniques, including histology, immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and Western blot analysis. RESULTS: p53+/+ allografts ceased beating at 7.6+/-0.5 days, whereas p53-/- hearts were beating at 10.5+/-1.1 days after transplantation (P<0.01). Mean histological rejection scores were significantly lower in allografts donated by p53-deficient mice. Furthermore, apoptotic cells, determined by TUNEL and a reagent kit for detection of cardiac apoptosis, were of high numbers in the allograft sections from wild-type hearts but rare in p53-/- allografts (4.2+/-1.3 vs. 0.7+/-0.5/250x field). Immunofluorescence staining and Western blot analysis revealed that high levels of p53 and proapoptotic protein Bax were expressed in wild-type grafts but not p53-/- allografts. Interestingly, Bcl-2, an antiapoptotic protein, was abundant in cardiac allografts from p53-/- mice and almost undetectable in grafts from wild-type mice. CONCLUSIONS: Thus, p53 is involved in cardiac apoptosis induced by alloimmune reaction, and prolonged survival of heart allografts can be achieved when p53 is lacking.     

Indefinite survival of rat islet allografts following infusion of donor bone marrow without cytoablation

We have tested the effect of donor bone marrow cell (DBMC) infusion on the survival of pancreatic islet allografts in the rat, without the use of cytoablative recipient conditioning. Lewis and diabetic Brown Norway rats were used as donors and recipients, respectively. Donor islets were placed beneath the left renal capsule. Infusion of DBMC and temporary immunosuppression followed by delayed islet transplantation resulted in indefinite survival of all islet grafts (MST >180 days). Control animals demonstrated recurrent hyperglycemia (islet allografts rejection). Donor bone marrow derived cells were detected in the spleen and cervical lymph nodes of BN recipients of LEW bone marrow but not in the recipients of islet transplants alone. Second set full thickness skin grafts were performed in normal BN and in recipients of a previously successful ITX. Donor specific skin grafts were accepted in the animals that had received DBMC 40 days before the islet allograft, while animals receiving DBMC at the time of the islet allograft rejected the donor specific skin graft similarly to the controls. However, these animals did not reject a second set donor-specific islet transplant. The results indicate that radiation conditioning of the recipients was not necessary to induce microchimerism and graft acceptance in this rodent model of islet allotransplantation.     

Role of CXCR3 and CCR5 in allograft rejection

Chemokines are known to participate in allograft rejection by mediating leukocyte trafficking. Despite redundancy in chemokine family, several chemokine-chemokine receptor interactions have proven critical in alloimmune responses. We sought to determine the effect of combined blockade of CXCR3 and CCR5, two critical chemokine receptors, in acute rejection. METHODS: Heterotopic heart transplantation was performed using BALB/c to B6/129 mice deficient in CCR5. Following transplantation these mice were treated with goat anti-CXCR3 serum every other day. In the control group, BALB/c hearts were transplanted in wild type B6/129 recipients and treated with goat serum alone. No immunosuppression was given to either group. Recipient mice were then assessed daily for allograft function by abdominal palpation, and graft survival was confirmed by laparotomy. RESULTS: The donor hearts in the control group were rejected at 6 +/- 1 days posttransplantation. Combined blockade of CXCR3 and CCR5 prolonged allograft survival versus control; all allografts survived to 24 days. In addition, there was a decrease in graft infiltrating CD4 and CD8 lymphocytes in the experimental group at 24 days. CONCLUSION: Combined CXCR3 and CCR5 blockade is effective in prolonging allograft survival in a fully MHC mismatched murine model. Combined chemokine blockade holds promise in control of acute rejection in organ transplantation.     

Liver allografts are toleragenic in rats conditioned with posttransplant total lymphoid irradiation

BACKGROUND: Posttransplant total lymphoid irradiation (TLI) treatment has been applied to tolerance induction protocols in heart and kidney transplantation models. METHODS: We examined the efficacy and mechanism of posttransplant TLI treatment in the induction and maintenance of tolerance in a rat orthotopic liver transplantation model. RESULTS: Posttransplant TLI prolonged ACI (RT1(a)) liver allograft survival in Lewis (RT1(b)) hosts, with 50% long-term engraftment without immunosuppression and without evidence of chronic rejection. Injection of donor-type liver mononuclear cells (LMCs) facilitated the prolongation of graft survival, with more than 70% of grafts in LMC recipients surviving more than 100 days without chronic rejection. Recipients with long-term liver allograft survival accepted ACI but not PVG skin grafts. In TLI-conditioned recipients with accepted grafts, apoptosis occurred predominantly in graft-infiltrating leukocytes. In contrast, there were few apoptotic leukocytes in rejecting grafts. Recipients with long-term graft acceptance (>100 days of survival) demonstrated evidence of immune deviation; mixed lymphocyte reaction to ACI stimulator cells was vigorous, but secretion of interferon-gamma and interleukin-2 was reduced. In tolerant recipients, the number of Foxp3(+) CD25(+) CD4(+) regulatory T cells was increased in the liver allograft as well as in the peripheral blood. CONCLUSION: We conclude that posttransplant TLI induces tolerance to liver allografts via a mechanism involving apoptotic cell-deletion and immunoregulation.     

The Effect of a Novel Immunosuppressant, FTY720, in Mice Without Secondary Lymphoid Organs

Purpose FTY720 is a novel immunosuppressive agent that is thought to reduce the number of peripheral blood lymphocytes (PBL) by directing them toward secondary lymphoid organs such as the lymph nodes and Peyer’s patches. We studied the effects of FTY720 on aly/aly mice that do not have either lymph nodes or Peyer’s patches, as well as on splenectomized aly/aly mice.Methods FTY720 was orally administered by gavage (1 mg/kg) to aly/aly mice as well as to aly/+ mice with and without a splenectomy on 14 consecutive days. The number of lymphocytes was then counted using True Cell beads and flow cytometry. The number of B220-, CD3-, and CD4-positive cells was also determined. In addition, skin grafts from C3H donor mice were performed on these mice.Results FTY720 was effective in significantly reducing the total lymphocyte count as well as the B220-, CD3-, and CD4-positive subtypes in the peripheral blood of aly/+ mice as well as in aly/aly mice with and without a splenectomy. While we did observe allograft skin graft rejection in both the aly/+ mice as well as the aly/aly mice recipients and splenectomized aly/aly mice, the graft survival was prolonged in all groups. The skin allografts treated by FTY720 thus demonstrated fewer lymphocytic cells and less infiltration of CD4-positive cells.Conclusions The administration of FTY720 to mice without lymph nodes, Peyer’s patches, or spleens still results in peripheral lymphopenia. In all groups, FTY720 was found to prevent the infiltration of CD4-positive cells in skin allografts while also prolonging skin allograft survival. The fate of these lymphocytes, however, is unclear.     

抑制趋化因子受体CCR5减轻小鼠同种异体移植心脏急性排斥反应的研究

目的 研究抑制趋化因子受体CCR5减轻小鼠同种异体移植心脏急性排斥反应的作用机制.方法 采用小鼠颈部心脏移植模型,将96只小鼠用随机数字表法分为4组,每组24只,供、受者各12只,A组术后给予anti-CCR5 mAb和CsA,B组术后给予anti-CCR5 mAb,C组术后给予CsA,D组为对照组,术后给予生理盐水.于术后第7d取各组移植心组织6例,检测CCR5及IL-2和IL-10的表达差异,其余6例用于观察移植心脏存活时间.结果 A、B、C组小鼠移植心脏存活时间明显延长,其CCR5及IL-2的表达较D组明显减少,IL-10的表达明显增加.结论 抑制趋化因子受体CCR5对同种异体移植心脏有明显的保护作用,可能与细胞因子的表达有关.     

Sex-associated differences in the survival of skin grafts in rats. Enhancement of cyclosporine immunosuppression in male compared with female recipients

Focusing on sex-difference in prolongation of allograft survival time, we have performed skin grafts between fully allogeneic rat strains, AO (RT1u) and DA (RT1a) with an immunosuppressant, cyclosporine. Isografted skins survived indefinitely, whereas allografts were severely rejected at days 7-9 without immunosuppressive treatment. When adult male DA rats received CsA (15 mg/kg/day, i.m., for 14 days postoperatively), allogeneic skin was accepted from either male or female AO rats for 38.8 +/- 20.5 days (mean survival time [MST] +/- SD) and for 44.7 +/- 43.3 days (MST +/- SD), respectively, with normal hair growth at around day 17. Additional CsA administration every 5 days after the initial short course treatment was also effective in preventing chronic rejection. Male AO rat skin grafted onto adult male DA rats survived for over 50 days as long as the treatment was carried out. In contrast, when adult female DA rats were used as recipients, only a few days' prolongation was observed in comparison with a non-treated group. The rejection always occurred, even during the initial course of treatment (MST +/- SD): 10.9 +/- 1.6 days). Younger male DA recipients, 5 and 10 weeks old, rejected AO skin within a shorter time, depending on the age. The maximal graft survival was observed when male adult rats more than 14 weeks old were used as recipients. On the other hand, the CsA serum level of female recipients at day 14 was considerably lower than that of males. However, even when the level of females was adjusted to that of males by the administration of a double dosage (30 mg/kg/day), the female recipients consistently rejected the skins (MST +/- SD: 14.5 +/- 1.9 days). Therefore, these results clearly indicate that this male-associated immunosuppressive effect depends upon the sex and age of the recipient animals.     

外用环孢素A联合CTLA4Ig延长异体移植鼠耳存活的研究

目的　探讨局部外用环孢素 A(Cs A)联合细胞毒性淋巴细胞相关抗原 4融合蛋白 (CTL A4 Ig)对异体复合组织移植的免疫抑制及诱导免疫耐受的作用。方法　建立吻合血管的同种异体大鼠耳廓移植模型 ,术后在移植耳皮肤表面外涂 Cs A并联合 CTL A4 Ig腹腔注射治疗 ,观察移植物的排斥反应及存活时间 ,检测移植后受体血清白细胞介素 - 2 (IL- 2 )含量变化。结果　对照组平均存活时间为 (7.8± 1.7)天 ;单纯用 Cs A治疗组为 (15 .2± 1.9)天 ,单纯CTL A4 Ig治疗组为 (16 .6± 2 .1)天 ;Cs A +CTL A4 Ig联合治疗组为 (2 8.8± 3.5 )天 ,与其它各组相比均有统计学意义 (P<0 .0 1) ;且联合治疗组的受体血清 IL - 2含量最低 ,尤以第 5、7天为著 ,与其它各组相比有统计学意义 (P<0 .0 1)。结论　局部外用 Cs A联合 CTL A4 Ig能有效抑制异体复合组织移植排斥反应 ,显著延长移植物存活时间。