Beneficial effects of costimulatory blockade with anti-inducible costimulator antibody in conjunction with CTLA4Ig on prevention of islet xenograft rejection from rat to mouse

BACKGROUND: Costimulatory signals have been reported to play an important role in islet-xenograft rejection, although the precise mechanisms remain unknown. The aim of the present study was to determine a role of a novel costimulatory molecule, inducible costimulator (ICOS), in rat islet-xenograft rejection in conjunction with CTLA4Ig with respect to cellular as well as humoral immune responses. METHODS: Isolated rat islets were transplanted into the liver of streptozotocin (180 mg/kg) induced diabetic mice. Cellular immune responses to islet xenografts, and productions of anti-rat antibody in mice were examined by flow cytometry (FACS) after transplantation. RESULTS: Intrahepatic rat islet xenografts were rejected in mice within 8 days after transplantation. FACS analysis revealed an expansion of CD8(+) T cells in the liver as well as a production of anti-rat antibody in recipient mice in association with rejection. The treatment with anti-ICOS antibody in conjunction with CTLA4Ig produced a marked prolongation of islet-xenograft survival with neither expansion of CD8(+) T cells nor production of anti-rat antibody, whereas, in contrast, those treated with anti-ICOS antibody or CTLA4Ig alone did not have prolonged survival, and CD8(+) T cells were expanded. CONCLUSION: These findings demonstrate that cellular rather than humoral immune responses are considered responsible for islet-xenograft rejection from rat to mouse and that the blockade of costimulatory signals with anti-ICOS antibody in conjunction with CTLA4Ig has a favorable effect on prevention of islet xenograft rejection.     

Multiple Combination Therapies Involving Blockade of ICOS/B7RP-1 Costimulation Facilitate Long-Term Islet Allograft Survival

In recent years a series of novel costimulatory molecules have been identified, including inducible costimulator (ICOS). In a fully major histocompatibility complex (MHC)-mismatched mouse model of islet transplantation, we demonstrate that while monotherapy with CTLA4-Ig, CD40 ligand monoclonal antibody (CD40L mAb) or rapamycin each improves islet allograft survival, graft rejection eventually develops. Immunohistologic analysis of rejected grafts revealed increased ICOS expression, suggesting a role for this costimulatory molecule as an alternate pathway for T-cell activation. The combination of a blocking anti-ICOS mAb with each of the above therapies resulted in significantly improved islet allograft survival, confirming the importance of ICOS signaling in islet allograft rejection. Mechanistic studies conducted in mice treated with anti-ICOS mAb and rapamycin demonstrated a lack of donor-specific immunological tolerance and an absence of regulatory T-cell activity. However, a dramatic effect was seen on acute anti-donor responses whereby anti-ICOS mAb and rapamycin significantly reduced the initial expansion and function of alloreactive T cells. These data demonstrate that blockade of the ICOS/B7RP-1 pathway has potential therapeutic benefit given its role in enhancing islet allograft survival and regulating acute alloresponses in vivo.     

Prolonged survival in rat liver transplantation with mouse monoclonal antibody against an inducible costimulator (ICOS)

BACKGROUND: An inducible costimulator (ICOS), a recently identified costimulatory receptor with a close structural homology to CD28 and CTLA4, is expressed on activated T cells. Interaction with its ligand on antigen-presenting cells stimulates T-cell proliferation to produce a different spectrum of cytokine. The inhibition of ICOS-mediated signal transduction by an anti-ICOS antibody is considered to be capable of protecting against graft rejection in organ transplantation. METHODS: An anti-rat ICOS antibody was intravenously administered into recipients of dark Agouti-to-Lewis liver transplantations. The recipient lymphocytes from mesenteric lymph nodes were harvested on day 7 after transplantation for fluorescence-activated cell sorting analysis, and tissue specimens from the grafts were removed for histologic evaluation. Antigen-specific T-cell proliferation responses were assessed in vitro with anti-ICOS antibody. RESULTS: Monotherapy with the antibody significantly prolonged the graft survival time by inhibiting T-cell activation and its proliferation response. The graft-infiltrating cells, both CD4 and CD8 T cells, were not completely reduced even when rats were administered the antibody, whereas the expression of ICOS almost completely disappeared in these cells. CONCLUSIONS: T-cell activation through the ICOS costimulatory pathway plays an important role in graft rejection, and manipulating its pathway is an effective method for modulating transplantation immunity.     

Significant enhancement by anti-ICOS antibody of suboptimal tacrolimus immunosuppression in rat liver transplantation.

A member of the costimulatory molecule family, inducible costimulator (ICOS), is expressed on activated T cells and plays a critical role in their primary activation and cytokine production. ICOS is involved in different immune phenomena, such as Th1-mediated autoimmune disease and graft rejection. Although blockade of ICOS costimulation theoretically may protect grafts from rejection, a single dose of anti-ICOS antibody did not result in the prolongation of rat liver allograft survival. However, in this article, we report that anti-rat ICOS antibody markedly enhanced the immunosuppressive activity of a suboptimal dose of tacrolimus (FK506). After fully allogenic DA to LEW liver transplantation, recipients received a single injection of tacrolimus (1 mg/kg, intramuscularly) with or without anti-ICOS antibody (1 mg/kg, intravenously). Recipient survival was significantly prolonged in rats treated with both the antibody and suboptimal tacrolimus (median survival time 44 days vs. 28 days with tacrolimus alone, P <.01). The extent of cell infiltration into the graft was closely associated with prolongation of recipient survival. Our findings thus demonstrate that anti-ICOS antibody immunotherapy combined with suboptimal tacrolimus has a synergistic effect in preventing hepatic allograft rejection and that it may induce long-term graft acceptance intimately associated with a marked reduction of intragraft T lymphocyte infiltration.     

Induction of immunologic tolerance to cardiac allograft by simultaneous blockade of inducible co-stimulator and cytotoxic T-lymphocyte antigen 4 pathway

BACKGROUND: Inducible co-stimulator (ICOS) is one of the most recently described members of the CD28 family, and it plays an important role in immune responses. To investigate the role of ICOS in allograft rejection, the authors studied graft survival after cardiac transplantation in mice. METHODS: Hearts from BALB/c mice were transplanted into C3H/He mice. Immunohistochemical staining and flow cytometry were performed. Monoclonal antibody to ICOS or ICOS-immunoglobulin (Ig) was injected intraperitoneally. The authors performed mixed lymphocyte reaction (MLR). RESULTS: ICOS was expressed strongly by graft-infiltrating cells during rejection of the allograft. Blockade of the ICOS pathway with anti-ICOS antibody and ICOSIg significantly prolonged graft survival time relative to that in untreated mice; however, all cardiac allografts were eventually rejected by a single treatment. Treatment with both ICOSIg and cytotoxic T-lymphocyte antigen 4 (CTLA4) Ig induced not only long-term acceptance of the cardiac allograft but also donor-specific tolerance, which was shown by acceptance of donor but not third-party skin. Graft arterial intimal hyperplasia in these cardiac allografts was remarkably less than that in cardiac allografts treated with tacrolimus. Addition of anti-ICOS antibody or ICOSIg to MLR resulted in inhibition of T-cell proliferation. CONCLUSIONS: Inhibition of T-cell proliferation with ICOSIg and CTLA4Ig was more effective than that with ICOSIg alone. Thus, ICOS appears to be an important regulator of T-cell activation, and may be an effective therapy in clinical cardiac transplantation.     

Prolongation of rat islet xenograft survival in the liver of IFN-gamma-deficient mice

The cellular mechanisms involved in islet xenograft rejection remain undetermined. In the present study, the role of interferon-gamma (IFN-gamma) in rat islet xenograft rejection was examined with the use of IFN-gamma-deficient mice as recipients and the results were compared with allografts. There was no significant difference in the survival of intrahepatic islet allografts in IFN-gamma-deficient mice compared with that in wild-type mice. In contrast, a marked prolongation of rat islet xenograft survival was obtained in IFN-gamma-deficient mice without immunosuppression when compared with the survival in wild-type mice. In order to dissect the difference, infiltrating cells in the liver in association with rejection were examined with flow cytometry. An expansion of CD8 T cells was seen in the liver of wild-type mice rejecting xenografts compared with isografts. There was no significant change in other cell populations. In IFN-gamma-deficient mice, the expansion of CD8 T cells was seen in the liver rejecting xenografts; however, the time of development was markedly delayed by the time of rejection. These findings suggest that the acute rejection of rat islet xenografts in mice is IFN-gamma-dependent although the exact mechanisms remain unknown.     

Further study of anti-ICOS immunotherapy for rat cardiac allograft rejection

PURPOSE: To study the effect of B7-CD28 costimulatory signal blockade by adenovirus-mediated cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin (AdCTLA-4Ig) on cardiac allograft survival in DA (RT1(a)) to LEW (Lewis RT1(l)) rat combinations. METHODS: We evaluated the effect of combined AdCTLA-4Ig and anti-inducible costimulator (ICOS) antibody immunotherapy on rat cardiac allograft acceptance. RESULTS: Unlike AdCTLA-4Ig alone, anti-ICOS immunotherapy combined with AdCTLA-4Ig induced stable tolerance without causing chronic rejection. The combined immunotherapy also prevented the accelerated cardiac rejection caused by donor-type test skin grafting. Immunohistochemical analyses revealed remarkable inflammatory mononuclear cell infiltration with typical vasculopathy, especially ICOS-positive cells in the grafts, in recipients treated with AdCTLA-4Ig alone. In contrast, anti-ICOS therapy combined with AdCTLA-4Ig reduced the ICOS-positive inflammatory cell infiltration of the graft significantly. The most important finding is that possible cardiac arrest caused by secondary donor-type skin graft was prevented by combined immunotherapy of AdCTLA-4Ig and anti-ICOS antibody, despite skin graft rejection. CONCLUSIONS: Our results identified a major role played by the ICOS-ICOSL pathway in chronic and accelerated cardiac allograft rejection, providing a novel approach to preventing the chronic rejection of vascularized organ allografts.     

Combination therapy with anti-ICOS and cyclosporine enhances cardiac but not islet allograft survival

The blockade of costimulatory signals is a powerful strategy to prevent allograft rejection and facilitate transplantation tolerance. In recent years, a series of novel costimulatory molecules have been identified, including an inducible costimulatory molecule (ICOS). To date, little has been uncovered regarding the therapeutic potential of blocking ICOS signaling in the setting of transplantation. In a fully MHC-mismatched mouse model, we studied the effect of blocking ICOS signaling using a specific monoclonal antibody (anti-ICOS mAb) in combination with cyclosporine on cardiac and islet allograft survival. We demonstrated that combined treatment with anti-ICOS mAb and cyclosporine can induce long-term graft acceptance in cardiac but not islet allografts, suggesting that the type of transplanted tissue significantly influences the immunologic patterns of graft acceptance or rejection in this model.     

Natural killer T-cells participate in rejection of islet allografts in the liver of mice

A role of natural killer T (NKT) cells in transplant rejection remains unknown. Here, we determined whether NKT cells participate in rejection of islet allografts, using NKT cell-deficient mice. Survival of islet allografts in streptozotocin-induced diabetic CD1d(-/-) mice or Valpha14 NKT cell(-/-) mice was significantly prolonged without immunosuppression when grafted into the liver, but not beneath the kidney capsule, compared with wild-type mice. Acceptance of intrahepatic islet allografts was achieved in CD1d(-/-) mice by a subtherapeutic dose of rapamycin, which was abrogated in conjunction with the transfer of hepatic mononuclear cells from wild-type, but not from CD1d(-/-), mice at islet transplantation. The second islet grafts from a donor-specific, but not from a third-party, strain in CD1d(-/-) mice bearing functional islet allografts were accepted without immunosuppression at 120 days after the initial transplantation. These findings demonstrate that NKT cells play a significant role in rejection of islet allografts in the liver of mice, but that NKT cells are not essential for induction of donor-specific unresponsiveness in this model. The current study indicates that NKT cells might be considered as a target for intervention to prevent islet allograft rejection when the liver is the site of transplantation.     

Costimulation blockade of both inducible costimulator and CD40 ligand induces dominant tolerance to islet allografts and prevents spontaneous autoimmune diabetes in the NOD mouse

Costimulation blockade is a promising strategy for preventing allograft rejection and inducing tolerance. Using a fully allogeneic mouse model, we tested the effectiveness of the combined blockade of the CD40 ligand and the inducible costimulator (ICOS) on islet allograft survival and in the prevention of autoimmune diabetes in the NOD mouse. Recipients treated with blocking monoclonal antibodies (mAbs) to ICOS and the CD40 ligand had significant prolongation of graft survival, with 26 of 28 functioning for >200 days. Long-term engrafted mice maintained antidonor proliferative and cytotoxic responses, but donor-specific immunization did not induce graft rejection, and challenge with second, same donor but not third-party grafts resulted in long-term acceptance. The immunohistology of tolerant grafts demonstrated the presence of CD4(+)CD25(+) T-cells expressing Foxp3, and islet/kidney composite grafts from tolerant mice, but not from mice lacking lymphocytes, were accepted indefinitely when transplanted into na?ve B6 mice, suggesting that recipient T-cells were necessary to generate dominant tolerance. Combined anti-ICOS and anti-CD40 ligand mAb therapy also prevented diabetes in NOD mice, with only 11% of treated recipients developing diabetes compared with 75% of controls. These data demonstrate that the blockade of CD40 ligand and ICOS signaling induces islet allograft tolerance involving a dominant mechanism associated with intragraft regulatory cells and prevents autoimmune diabetes in NOD mice.     

Inhibition of chronic rejection and development of tolerogenic T cells after ICOS-ICOSL and CD40-CD40L co-stimulation blockade

BACKGROUND.: Blockade of the CD40-CD40L pathway results in long-term allograft survival but does not prevent chronic rejection. ICOS-ICOSL are members of the CD28-B7 family that play an important role in T-cell activation. METHODS.: The authors analyzed the effect of single or combined treatment with an anti-ICOS monoclonal antibody and CD40 immunoglobulin (Ig) on acute and chronic rejection of heart allografts in rats. RESULTS.: Treatment with anti-ICOS resulted in a modest but significant prolongation of allograft survival. Treatment with CD40Ig resulted in long-term graft survival but the cardiac grafts developed chronic rejection lesions. Combined CD40Ig+anti-ICOS treatment led to indefinite graft survival in all recipients and a significant decrease of chronic rejection lesions compared with CD40Ig alone. Importantly, four of the seven CD40Ig+anti-ICOS-treated recipients showed a complete absence of chronic rejection lesions, whereas all of the CD40Ig-treated recipients showed chronic rejection. The CD40Ig+anti-ICOS group also showed significant decreased graft infiltration, decreased antidonor cytotoxic T-lymphocyte activity, and decreased alloantibodies compared with the CD40Ig-treated group. Adoptive transfer of splenocytes indefinitely prolonged allograft survival, whereas those depleted of T cells did not, suggesting the development of T-regulatory mechanisms. CONCLUSIONS.: These data indicate that the chronic rejection mechanisms that are CD40-CD40L independent are ICOS-ICOSL dependent. These results were obtained with conservation of cognate immune responses and development of tolerogenic T cells.     

AdCTLA-4Ig combined with donor splenocytes,bone marrow cells and anti-ICOS antibody treatment induce tolerance in a rat heart transplantation model

It is difficult to induce rat cardiac allograft tolerance by co-stimulator blockade of the B7-CD28 pathway with CTLA-4Ig monotherapy alone. However, combined therapies of AdCTLA-4Ig plus donor-specific spleen-cell infusion, bone marrow cell infusion, and anti–ICOS antibody have been demonstrated to effectively induce indefinite acceptance of rat cardiac allografts. In this report, we compared the tolerance of cardiac allograft tolerant recipients induced by the above three strategies. The results show that treating Lewis recipients of a DA cardiac allograft with a combination of AdCTLA4-Ig and anti-ICOS antibody, donor splenocytes or bone marrow cells produced indefinite graft survival. Second transplantation of donor type skin or heart grafts could not affect the survival of primary heart graft in anti-ICOS treated groups, but results in rejection of primary heart grafts in other two groups, and that co-stimulator blockade, CD28 and ICOS simultaneously with CTLA-4Ig and anti-ICOS antibody, facilitates the development of CD25+ CD4+ regulatory T cells and induces stable transplantation tolerance in the rat cardiac allograft model. This also provides an effective therapy in clinical transplantation for promoting permanent graft survival by generating regulatory T cells.Abbreviations BMC bone marrow cells - ICOS inducible co-stimulator - pfu plaque-forming units - SPC spleen cell     

Inhibition of chronic rejection and development of tolerogenic T cells after ICOS-ICOSL and CD40-CD40L co-stimulation blockade

BACKGROUND: Blockade of the CD40-CD40L pathway results in long-term allograft survival but does not prevent chronic rejection. ICOS-ICOSL are members of the CD28-B7 family that play an important role in T-cell activation. METHODS: The authors analyzed the effect of single or combined treatment with an anti-ICOS monoclonal antibody and the fusion molecule CD40 immunoglobulin (Ig) on acute and chronic rejection of heart allografts in rats. RESULTS: Treatment with anti-ICOS resulted in a modest but significant prolongation of allograft survival. Treatment with CD40Ig resulted in long-term graft survival but the cardiac grafts developed chronic rejection lesions. Combined CD40Ig+anti-ICOS treatment led to indefinite graft survival in all recipients and a significant decrease of chronic rejection lesions compared with CD40Ig alone. Importantly, four of the seven CD40Ig+anti-ICOS-treated recipients showed a complete absence of chronic rejection lesions, whereas all of the CD40Ig-treated recipients showed chronic rejection. The CD40Ig+anti-ICOS group also showed significant decreased graft infiltration, decreased antidonor cytotoxic T-lymphocyte activity, and decreased alloantibodies compared with the CD40Ig-treated group. Adoptive transfer of splenocytes indefinitely prolonged allograft survival, whereas those depleted of T cells did not, suggesting the development of T-regulatory mechanisms. CONCLUSIONS. These data indicate that the chronic rejection mechanisms that are CD40-CD40L independent are ICOS-ICOSL dependent. These results were obtained with conservation of cognate immune responses and development of tolerogenic T cells.     

Simultaneous blockade of co-stimulatory signals, CD28 and ICOS, induced a stable tolerance in rat heart transplantation

An inducible co-stimulator (ICOS), a recently identified co-stimulatory receptor with a close structural homology of CD28 and CTLA4, is expressed on activated T cells. Anti-ICOS antibody was demonstrated to be effective on prolongation of graft survival after liver transplantation in rats. In this study, we investigated the potency of tolerance induction using the antibody combined with a recombinant adenovirus vector containing CTLA-4Ig cDNA (AdCTLA-4Ig) in rat heart transplantation model. Using a DA-to-Lewis rat heart transplantation model, an anti-rat ICOS antibody and AdCTLA-4Ig were simultaneously administered i.v. into recipients. The tissue specimens from the grafts were removed on various days after transplantation for histological evaluation. Donor-strain skin and heart grafts, and third-party heart allografts were challenged in the recipients with a long-term surviving graft. Splenocytes from the tolerance-induced recipients were used for adoptive transfer study. Anti-ICOS antibody alone did not prolong the survival of heart allograft. AdCTLA-4Ig monotherapy significantly prolonged the survival of heart allograft (Group 4). With a combination of Anti-ICOS antibody and AdCTLA-4Ig, all recipients were resulted in a long-term allograft acceptance for more than 200 days (Group 8). When challenged donor-strain skin grafts in the tolerant rats of Group 4, the skin was rejected, which also lead to a rejection of primary heart allografts. The recipients in Group 8 also rejected donor-strain skin grafts with no rejection of the primary heart grafts. These recipients accepted secondary heart grafts from donor-strain but not third-party. In Group 8 long-term survival recipients showed a high population of CD4+CD25+ regulatory T cell in peripheral blood, and in adoptive transfer study subtraction of these CD4+CD25+ T cells accelerate the rejection of heart graft in secondary irradiated recipients. The present results demonstrated that anti-ICOS antibody combined with AdCTLA-4Ig potently induces a stable immune tolerance after heart allografting in rat, which is mediated by the induction of CD4+CD25+ regulatory T cells. This strategy may be attractive for clinical employment to induce transplantation tolerance.     

ICOS/B7RP-1 interference in mouse kidney transplantation

BACKGROUND: Activated T cells play a key role in allograft rejection. T cell activation requires signaling via the T cell receptor as well as costimulatory signals. Inducible costimulatory molecule (ICOS), with its ligand B7RP-1, is a recently discovered costimulatory molecule of the CD28 family. The role of this signaling pathway during the early phases of kidney allograft rejection is not clear so far. METHODS: Kidneys were orthotopically transplanted from BALB/c to C57BL/6 mice. Animals were assigned to five experimental groups: blocking anti-ICOS monoclonal antibody, ICOS fusion protein, anti-B7RP1 monoclonal antibody, B7RP-1 fusion protein, and control immunoglobulin G. RESULTS: Survival was significantly reduced in animals treated with ICOS monoclonal antibody (mAb) and B7RP-1 Fc as compared with controls. These animals had also a lower number of apoptotic graft infiltrating T cells, whereas the expression of intracellular interferon-gamma in CD3CD4 T cells was increased. Animals treated with ICOS Fc and B7RP-1 mAb had similar survival and numbers of apoptotic T cells as compared with controls. CONCLUSIONS: In summary, the blockade of ICOS with ICOS mAb or B7RP-1 Fc reduced the amount of apoptosis of infiltrating lymphocytes and resulted in continuous inflammatory processes with progressive tissue damage and graft failure.     

ICOS-Dependent and -Independent Functions of Memory CD4 T Cells in Allograft Rejection

Donor-reactive memory T cells undermine the survival of transplanted organs through multiple pathways. We have previously reported that memory CD4 T cells resist treatment with anti-CD154 antibody and donor-specific transfusion (DST/MR1) and promote cardiac allograft rejection via generation of effector CD4 T cells and alloantibody. We hypothesized that the helper functions of memory CD4 T cells are independent of T-cell costimulation through CD154 but instead are regulated by alternative costimulatory pathways. This study investigated how blocking ICOS/B7RP-1 interactions affects functions of donor-reactive memory CD4 T cells. Treatment with blocking anti-ICOS mAb synergized with DST/MR1 and prolonged mouse cardiac allograft survival despite the presence of donor-reactive memory CD4 T cells. While blocking ICOS did not diminish the expansion of preexisting memory CD4 T cells or the induction of allospecific effector T cells, it did inhibit recruitment of the activated memory and effector T cells into the graft. In addition, anti-ICOS mAb treatment in combination with DST/MR1 prevented help provided by memory CD4 T cells for production of donor-specific IgG antibody. These results demonstrate the potential efficacy of ICOS blockade in sensitized transplant patients and provide the foundation for rational use of ICOS blockade in combination with other graft-prolonging strategies.     

抗可诱导共刺激分子抗体对大鼠慢性移植肾肾病的影响

目的 探讨应用抗可诱导共刺激分子(ICOS)抗体阻断ICOS-BTRP-1共刺激通路对大鼠慢性移植肾肾病(CAN)的影响及其可能机制.方法 实验分为3组:(1)同系对照组,供、受者均为Wistar大鼠,进行肾移植;(2)同种对照组,以SD大鼠为供者,Wistar大鼠为受者进行肾移植,术后灌胃给予环孢素A(CsA),用10 d;(3)实验组,在同种对照组的基础上,于使用CsA后经腹腔注射抗ICOS单克隆抗体,2 mg/kg,2次/周,共用3个月.各组分别于术后4、8和12周,检测受者血清肌酐;观察移植肾的病理学变化;用免疫组织化学法检测移植肾和受者脾脏中ICOS的表达;检测移植肾组织中ICOS mRNA的表达.另取存活6个月的实验组和同系对照组大鼠,检测其外周血中CD4+CD25+T淋巴细胞的比例.结果 同系对照组术后各个时间点的血清肌酐变化不大;同种对照组血清肌酐明显升高,12周时达(310±18)μmol/L;实验组血清肌酐也呈上升趋势,但上升幅度明显低于同种对照组,至12周时为(122±13)μmol/L.术后12周时,同种对照组移植肾肾小球硬化率和Banff评分(总分)分别为(54.75±3.06)%和8.28±1.41,实验组为(15.05±1.64)%和6.13±1.00,两组比较,差异有统计学意义(P＜0.01).同系对照组受者脾脏边缘区可见ICOS表达,白髓区少见ICOS表达,该组移植肾内未见ICOS明显表达;在同种对照组,移植后各时间点移植肾和受者脾脏中都可见ICOS明显表达;实验组移植肾和受者脾脏内ICOS的表达明显下降,且主要表达于脾脏的白髓区,边缘区很少表达.术后4、8和12周时,实验组各个时间点ICOS mRNA的表达明显低于同种对照组.实验组存活＞6个月者外周血中CD4+CD25+T淋巴细胞的比例平均为13.5%,同系对照组平均为9.1%.结论 应用抗ICOS抗体阻断ICOS-B7RP-1共刺激通路可在一定程度上抑制CAN的进展,其机制可能与移植肾组织ICOS的表达受到抑制及ICOS在受者脾脏内的重新分布有关,其中也可能有CD4+CD25+调节性T淋巴细胞的参与.     

CD103分子介导CD8+T淋巴细胞对同种胰岛移植物的损伤

目的 检验CD103分子是否介导了CD8+T淋巴细胞对同种移植胰岛的免疫损伤.方法 用流式细胞仪检测野生型C57BL/6小鼠外周血CD8+T淋巴细胞表达CD103的情况.以Balb/c小鼠为供者,C57BL/6小鼠为受者,制作同种胰岛移植模型.受者分为3组:M290-SAP组小鼠注射CD103免疫毒素M290-SAP;M290组小鼠注射抗CD103单克隆抗体M290;另以仅接受胰岛移植、不注射任何药物的小鼠为未处理组.检测移植胰岛CD3、CD8、CD44和CD103阳性细胞的表达,检测肠系膜淋巴结中CD3、CD8和CD103阳性细胞的表达.移植物功能丧失或观察期结束时获取移植胰岛,行HE染色和免疫组织化学染色.结果 野生型C57BL/6小鼠外周血的CD8+T淋巴细胞中有44.06%表达CD103.未处理组移植胰岛浸润的细胞成分中有29%的CD8+T淋巴细胞表达CD103.M290-SAP组小鼠淋巴细胞不仅丧失了CD103的表达,而且CD8+T淋巴细胞的绝对数量也减少,该组小鼠血糖稳定时间超过100 d(未处理组为13 d,P＜0.05),移植胰岛组织学形态良好.结论 CD8+T淋巴细胞免疫损伤同种移植胰岛必须表达CD103,CD103有可能成为胰岛移植抗排斥反应治疗的新靶点.

Abstract：

Objective To test whether the CD103 molecule mediates CD8+ T lymphocytes on allogeneic islet graft immune injury. Methods By using flow cytometry, the expression of CD103 in peripheral CD8+ T lymphocytes in wild-type C57BL/6 mice was detected. Allogenic islet transplantation models were made using Balb/c donor mice and C57BL/6 recipient mice. Recipients were divided into 3 groups: M290-SAP-treated mice were injected with CD103 immunotoxin M290-SAP; M290-treated mice were injected with CD103 monoclonal antibody M290; untreated mice were only transplanted islet without any drug treatment. CD3, CD8, CD44 and CD103 positive cells were counted in islet allograft infiltrative lymphocytes. CD3, CD8, and CD103 positive cells were measured in the mesenteric lymph node. The islet allografts were removed and subjected to HE staining and immunohistochemical staining at the time of graft loss or the end of the observation period. Results 44. 06% peripheral CD8+ T cells expressed CD103 in wild-type C57BL/6 mice. 29 % CD8+ T cells expressed CD103 in the infiltrative lyrnphocytes of islet allografts in the untreated mice. In M290-SAP-treated mice, the lymphocytes had no CD103 expression and the absolute number of CD8+ lymphocytes was decreased as well The blood glucose was maintained stable for more than 100 days (13 days in untreated group, P＜0.05) in the M290-SAP-treated mice. Moreover, the transplanted islets retained intact. Conclusion CD103 expression is required for destruction of pancreatic islet allograft by CD8+ T cells. CD103 might provide a novel target for therapeutic intervention in islet allograft rejection.     

CD4+ T cell recognition of a single discordant HLA-A2-transgenic molecule through the indirect antigen presentation pathway induces acute rejection of murine cardiac allografts.

To further define the role of indirect allorecognition, cardiac allografts from HLA-A2-transgenic (HLA-A2+) C57BL/6 mice were heterotopically transplanted into normal C57BL/6, CD4 T cell-knockout (KO) C57BL/6 mice, CD8 T cell-KO C57BL/6 mice, fully MHC-discordant BALB/c mice (allogeneic control), and HLA-A2+ C57BL/6 mice (syngeneic control). HLA-A2+ grafts were acutely rejected when transplanted into BALB/c mice (mean survival time: 10+/-0.8 days), normal C57BL/6 mice (mean survival time: 16.5+/-2.1 days) as well as CD8-KO mice (mean survival time: 12.8+/-1.3 days). Histopathological analysis revealed classical acute cellular rejection with moderate to severe diffuse interstitial CD4+ and CD8+ cellular infiltrates and significant intra-graft deposition of IgG and complement. In contrast, HLA-A2+ grafts were not rejected when transplanted into CD4-KO mice or HLA-A2+ mice. CD8-KO recipients treated with an anti-CD4 monoclonal antibody, but not with an anti-NK monoclonal antibody, failed to reject their allografts with prolonged administration of antibody (30 days). Spleen cells from mice rejecting HLA-A2+ allografts failed to lyse HLA-A2+ target cells indicating a lack of involvement of CD8+ T cells in the rejection process. In contrast, spleen cells from rejecting animals proliferated significantly to both HLA-A2+ cells and to a peptide derived from the HLA-A2 molecule. Development of anti-HLA-A2 antibodies was observed in all animals rejecting HLA-A2+ allografts. These results suggest that indirect allorecognition of donor MHC class I molecules leads to rejection of cardiac allografts and development of alloantibodies in this unique transplant model in which there is a single MHC discordance between donor and recipient.     

Islet xenograft rejection in absence of CD8+ T cells does not require either interferon-gamma or interleukin-5

We recently demonstrated that interleukin-5 and eosinophils mediate rejection of skin allografts when CD8+ T cell-dependent and Th1-type CD4+ T cell-dependent pathways are not functional. The purpose of this study was to determine whether a similar mechanism might be operative during rejection of rat islet xenografts in mice. First, we observed that eosinophils indeed infiltrate rejected islet grafts together with CD4+ and CD8+ T cells. CD8+ T cell depletion significantly enhanced graft survival and a further prolongation of islet function was obtained in combination with interferon-gamma neutralization. However, islet rejection characterized by prominent eosinophil and macrophage infiltration still occurred in this setting. Although eosinophil infiltrates were dramatically reduced in interleukin-5 deficient mice, the ability of these animals to reject islet xenografts under CD8+ T cell depletion and interferon-gamma neutralization was similar to that of wild-type mice. We conclude that in absence of CD8+ T cells and interferon-gamma, macrophages, but not eosinophils, mediate rejection of rat-to-mouse islet xenografts.