人外周血T细胞系间接识别SLAⅠ类分子引起的异种细胞增殖反应

目的 确认猪→人异种移植中存在针对猪白细胞抗原(swine leukocyte antigen，SLA)Ⅰ类分子的间接识别而引起的急性细胞性排斥。方法 用纯化的中国版纳猪SLA Ⅰ类P1基因工程蛋白为抗原，体外反复刺激健康人外周血T细胞，建立P1特异性T细胞系。观察抗原特异性CD4 T细胞系在自身APC存在下对版纳猪外周血单个核细胞与软骨细胞的反应性，以及HLA-DR单抗与氯喹的阻断作用。结果 建立10株SLA Ⅰ类P1抗原特异性T细胞系，其中8株以TCRαβ CD4 为主要表型，将其合并使用。该CD4 P1特异性T细胞系在自身APC存在下对相同品系版纳猪PBMC与软骨细胞均产生显著增殖反应。经抗人HLA-DR单抗与氯喹处理均能明显阻断其增殖反应。结论 健康人外周血T细胞可通过间接识别SLAⅠ类抗原对版纳猪细胞产生明显应答。     

建立猪MHCⅠ类抗原特异性人T细胞系的探讨

目的　建立间接识别中国版纳猪SLAⅠ类P1分子的特异性人T细胞系的方法 ,以进一步研究SLAⅠ类分子的间接识别在猪→人异种细胞性排斥中的作用。方法　以E·coli中表达并纯化的SLAⅠ类分子P1为抗原 ,体外反复刺激健康人PBMC ,3H TdR掺入法筛选特异性增殖的T细胞 ,FACS作表型初步分析。结果　初步测定健康人外周血版纳猪SLAⅠ类P1分子特异性T细胞反应频率约 6 .67× 1 0 - 7,所建 4个T细胞系表型均为TCRαβ+ ,其中 3株以CD4+ 为主 ,1株以CD8+ 为主。结论　利用E .coli表达的纯蛋白抗原可建立间接识别版纳猪SLAⅠ类P1分子的特异性人T细胞系。     

人特异性T细胞系间接识别猪抗原

SLA (swineleukocyteantigen )特异性CD4+T细胞系和自身APC以及猪PBMC共同孵育时 ,T细胞增殖反应很强 ,而同仅有自身APC或猪PBMC刺激时的T细胞增殖有显著差异。提示抗原特异性CD4+T细胞系以间接途径识别SLA抗原。该识别能被抗人CD4和HLAII类抗体阻断 ,而抗SLAII类抗体阻断作用很弱 ,表明HLAII类分子在间接识别中起重要作用 ,这一结果不同于直接从外周血中分离的未经抗原致敏的T细胞。直接识别猪APC递呈的抗原。有可能异种移植初期以直接识别为主导 ,随着移植物存活时间的延长逐渐转为间接识别     

异种移植中急性细胞性排斥的研究进展

异种移植是极具应用价值的一个医学领域 ,当前异种移植主要以猪→人为研究对象 ,它的临床应用至少要克服超急性排斥、急性血管性排斥和急性细胞性排斥这三大障碍。本文就急性细胞性排斥方面的研究进展包括人T淋巴细胞对猪异种抗原的直接识别、间接识别以及NK细胞的作用等进行了综述     

异种移植中急性细胞性排斥的研究进展

异种移植是极具应用价值的一个医学领域，当前异种移植主要以猪→人为研究对象，它的临床应用至少要克服超急性排斥、急性血管性排斥和急性细胞性排斥这三大障碍。本文就急性细胞性排斥方面的研究进展包括人T淋巴细胞对猪异种抗原的直接识别、间接识别以及NK细胞的作用等进行了综述。     

116异种移植中急性细胞性排斥的研究进展

异种移植是极具应用价值的一个医学领域,当前异种移植主要以猪→人为研究对象,它的临床应用至少要克服超急性排斥、急性血管性排斥和急性细胞性排斥这三大障碍.本文就急性细胞性排斥方面的研究进展包括人T淋巴细胞对猪异种抗原的直接识别、间接识别以及NK细胞的作用等进行了综述.     

异种移植细胞型排斥反应研究进展

同种移植的成功导致了器官需求增加,人供体器官的严重短缺使器官移植作为终末期器官病变的一种有效治疗措施受到限制。异种移植包括移植细胞、组织和器官,在不同的物种间已作为一种潜在的方法运用于临床,以克服人体材料的极端短缺。猪作为一种供体源的主要障碍在于存在着异种移植排斥反应,包括超急性排斥反应、延迟性排斥反应、T细胞排斥反应,和其他的生物学障碍如分子不相容性。目前对异种移植排斥反应的机制研究较多,形成了一些有效的防治措施。运用转染人延迟加速因子的转基因猪心脏移植到灵长类动物实验,说明异种移植超急性排斥反应已能克服,但实验动物数周后死于急性血管排斥反应,说明在超急性排斥反应克服以后,细胞型排斥反应将是异种移植的主要障碍。本文着重综述细胞型排斥反应的相关进展。     

调节性T细胞及相关细胞因子与同种小肠移植耐受

许多对于宿主免疫耐受中调节性T细胞作用的研究提供了大量有意义的结果。在小肠移植，抗CD4mAb和抗CD8mAbs均抑制排斥，但抗CD4mAb更有效；CD4^ CD25^T细胞的免疫抑制性表现在经TCR介导信号刺激活化以后能够抑制CD4^ 和CD8^ T细胞的活化和增殖，从而抑制排斥反应的发生实现耐受；调节性T细胞分泌的关键细胞因子与小肠移植排斥反应的发生、发展密切相关。通过少量关键的相关细胞因子改变免疫反应，成为实现同种小肠移植耐受的具有高度可行性的重要方法。     

修饰CⅡTA基因抑制异种器官移植中供体猪SLA的表达

目的 构建可抑制猪MHC（SLA）Ⅱ类分子表达的MHCⅡ类分子反式激活因子（CⅡTA）突变体，抑制人CD4^ T细胞对猪细胞株的免疫应答，为异种器官的应用研究奠定基础。方法 用PCR，人工合成寡核苷酸，限制性内切酶等技术构建不含起始密码子的pcDNA3mCⅡTA2，含起始密码子的pcDNA3mCⅡTA3突变体。用脂质体转染法将上述2种突变体及pcDNA3空载体转入猪细胞株PIEC细胞和L23细胞。用流式细胞术和RT-PCR法观察它们对PIEC/L23细胞SLA-DR/DQ分子的诱导性和组成性表达的影响。通过混合淋巴细胞反应观察人CD4^ T细胞对转入突变体及空载体后的猪细胞的免疫应答强度的变化。结果 在细胞和分子水平证实pcDNA3空载体无此作用。SLAⅡ类分子受抑制的猪细胞已基本丧失了对人CD4^ T细胞的刺激能力。结论 转染能抑制SLAⅡ类分子表达的突变体使PIEC细胞丧失了对人CD4^ T细胞的刺激能力，为异种器官的修饰提供了新的思路。     

两株抗人CD40配体单克隆抗体的制备及生物学特性的研究

目的 :研制功能性抗CD4 0L单克隆抗体 ,探讨其生物学特性及其运用价值。方法 :采用B淋巴细胞融合、免疫荧光、免疫印迹和竞争抑制等方法获得鼠抗人CD4 0LmAb ,通过Daudi细胞生长抑制试验、混合淋巴细胞反应观察抗CD4 0LmAb的生物学功能。结果 :经表型分析、Westernblot和竞争抑制试验 ,证实mAbB1、mAb4F1是识别人CD4 0L分子的特异性单抗 ,且识别的位点不同 ;mAbB1、mAb4F1均能不同程度地拮抗CD4 0L TC介导的Daudi细胞生长抑制和抑制混合淋巴细胞反应。结论 :成功地获得两株能稳定分泌特异性抗人CD4 0L单克隆抗体的杂交瘤 (1B1、4F1) ,这两株单抗对CD4 0L的生物学功能具有明显的阻断作用 ,为阻断型单抗     

ECDI偶联的人抗原提呈细胞诱导供者抗原特异性CD8+ T细胞耐受的实验研究

目的：研究体外模拟异基因移植环境下,碳二亚胺（ECDI）偶联的供者抗原提呈细胞（ECDI-APCs）诱导受者T细胞针对供者抗原特异性耐受的效果。方法：每组以HLA-A、-B、-DR完全错配的3名志愿者外周血淋巴细胞建立混合淋巴细胞培养体系,模拟异基因移植环境。在-6 d将受者外周血单个核细胞（PBMCs）与供者ECDI-APCs共培养,第0天再次加入新鲜分离的原供者APCs或无关供者APCs模拟移植,第8天以流式细胞术检测受者T细胞的增殖情况。结果：ECDI偶联浓度为150 mg/ml,供、受者细胞共培养比例为0.1∶1时,ECDI-APCs可诱导出受者T细胞对原供者抗原刺激的耐受状态（P<0.05）,其中受者CD8⁺ T细胞的耐受具有供者抗原特异性（P<0.05）,而CD4⁺ T细胞的耐受无抗原特异性（P>0.05）。结论：ECDI-APCs能诱导CD8⁺ T细胞对同种异体抗原刺激的耐受状态,并且具有供者抗原特异性,可为临床器官移植术后供者抗原特异性耐受的建立提供实验依据。     

Human natural killer cells enhance a mixed leukocyte reaction

Natural killer cells (NK) have been reported to down-regulate the initiation of T cell responses in animal models. In the current study, highly purified CD16+ human NK cells were obtained by cell sorting and their effect on the stimulation of allogeneic T cells (MLR) determined. NK cells did not directly stimulate T cell proliferation. However, when added to a population of loosely adherent mononuclear cells (LAM), NK enhanced the ability of these accessory cells to stimulate T proliferation. This effect was not reproduced by the addition of sorted CD5 + T cells, sorted CD16- cells, or control lymphocytes to the MLR. The effect of NK on the MLR was not restricted by class II antigens and was similar to the effect of adding IL-1 to MLR cultures. These results demonstrate that human NK cells are capable of enhancing a T cell response.     

CD57+ T cells augment IFN-gamma production in a one-way mixed lymphocyte reaction and their expansion after stem cell transplantation in paediatric patients

To clarify the immune response of CD57+ T cells (most of them are CD8+) in peripheral blood (PB) against alloantigens in order to elucidate the T helper 1 (Th 1) immune response, we assessed the role of CD57+ T cells in IFN-gamma (one of the representative Th 1 cytokines) production in a one-way mixed lymphocyte reaction (MLR). In this study, we showed that CD57+ T cells in responder cells were essential for effective IFN-gamma production in allogeneic MLR due partly to the augmentation of the alloresponse of regular T cells. Furthermore, IFN-gamma production in MLR correlated with the proportions of CD57+ T cells in PB regardless of the responders' age. We also showed that the extent of the expansion of CD57+ T cells in paediatric patients after haematopoietic stem cell transplantation (HSCT) was markedly lower than that in adult patients. In addition, CD57+ T cells purified and activated with a combination of cytokines showed a greater cytotoxicity than regular T cells against human umbilical vein endothelial cells. Because IFN-gamma production in one-way MLR is a useful predictor of graft-versus-host disease (GVHD), especially in the acute phase that occurs after allogeneic HSCT, our findings suggested that CD57+ T cells play a role in the development of GVHD and thus may explain the reason as to why a higher donor age is associated with an increased risk of developing GVHD while, in addition, the incidence of severe GVHD in paediatric patients is lower than that in adult patients.     

CD59a deficient mice display reduced B cell activity and antibody production in response to T-dependent antigens

CD59a is the primary regulator of membrane attack complex in mice. Recently, we have shown that CD59a-deficient (Cd59a-/-) mice exhibit enhanced CD4+ T cell responses. Here, we explored the effects of CD59a on B cell function and antibody production. Contrary to our expectations, Cd59a-/- mice showed a decreased humoral immune response to a T cell dependent antigen, sheep red blood cells. We found that the decreased humoral immune response was associated with a reduction in plasma cell number in vivo and reduced ability to respond to stimuli during in vitro culture experiments. Using MLR studies in which purified wild type or Cd59a-/- CD4+ T cells were mixed with purified B cells from each source, we found that the reduced B cell activation was largely due to the absence of CD59a on CD4+ T cells. Furthermore, a CD59a fusion protein bound specifically to mouse B cells, and enhanced B cell proliferation in a MLR, demonstrating that B cells express an as yet unidentified ligand for CD59a that aids in B cell activation.     

The direct pathway of human T-Cell allorecognition is not tolerized by stimulation with allogeneic peripheral blood mononuclear cells irradiated with high-dose ultraviolet B

Transfusions of high-dose (> or =10,000 Joule/m(2)) ultraviolet-B (UVB)-irradiated allogeneic leukocytes in rodent models have been shown to induce immunologic tolerance that is mediated by allospecific regulatory CD4(+) T cells. Whether these regulatory T cells recognize alloantigens through the direct or indirect pathway of allorecognition is controversial. Here, we demonstrate that the proliferative response obtained in standard primary mixed leukocyte reactions (MLRs) with human peripheral blood mononuclear cells (PBMCs) reflected a CD4(+) T-cell-dependent direct pathway of allorecognition and that high-dose UVB irradiation of PBMCs totally inhibited their capacity to induce a proliferative alloresponse. Re-stimulation with gamma-irradiated PBMCs from the same allogeneic donor (secondary MLR) elicited a proliferative and Th1-deviated response that was similar to the response induced in unprimed PBMCs. Finally, high-dose UVB was found to induce a rapid and massive apoptosis of irradiated PBMCs. Collectively, these data indicate that leukocytes irradiated with high-dose UVB are unable to prime for unresponsiveness or immune deviation in T cells directly recognizing allogeneic major histocompatibility complex molecules. Because it is well-established that antigens within transfused apoptotic cells are captured by resident tolerogenic spleen dendritic cells, we propose that tolerance induced by transfusions of high-dose UVB-irradiated leukocytes primarily involve T cells indirectly recognizing alloantigens.     

An allelic non-histocompatibility antigen with wide tissue distribution as a marker for chimerism in pigs

It is frequently useful in studies of transplantation to have available an antibody to a cell surface antigen, which is not itself responsible for transplant rejection. In this paper, we identify and describe such an antibody/antigen system in miniature swine. The monoclonal antibody, 1038H-10-9, was found to react to a pig allelic antigen (called PAA), found on a variety of pig cells and tissues, including peripheral blood mononuclear cells (PBMC), thymocytes, lymph node, bone marrow, and skin. Analysis for recipient sensitization against PAA was performed by in vitro cell-mediated lympholysis (CML) assay, mixed lymphocyte reaction (MLR) assay, antibody binding studies, and skin graft rejection patterns were examined. No evidence was found to indicate detection of PAA by any of these assays of alloreactivity. We therefore conclude that PAA is an allelic swine cell surface antigen, with wide tissue distribution, and that it is not a histocompatibility antigen. It should provide a powerful tool for studies of transplantation biology in miniature swine, such as identification and quantification of chimerism following organ transplantation.     

Dermal Microvascular Injury in the Human Peripheral Blood Lymphocyte Reconstituted-Severe Combined Immunodeficient (HuPBL-SCID) Mouse/Skin Allograft Model Is T Cell Mediated and Inhibited by a Combination of Cyclosporine and Rapamycin

We have analyzed the mechanism of human endothelial injury in a human peripheral blood lymphocyte-severe combined immunodeficient (huPBL-SCID) mouse/human skin graft model of allograft injury and examined the effect of immunosuppressive drugs on this process. In this model, split-thickness human skin containing the superficial dermal microvessels was grafted onto immunodeficient C.B-17 SCID or SCID/beige mice and allowed to heal. Human peripheral blood mononuclear cells (PBMCs) allogeneic to the skin, when subsequently introduced by intraperitoneal injection, caused destruction of the human dermal microvasculature by day 16, evident as endothelial cell sloughing and thrombosis. In the same specimens, mouse microvessels that invaded the human skin graft were uninjured. Human microvascular cell injury was accompanied by a mononuclear cell infiltrate consisting of approximately equal numbers of human CD4+ and CD8+ T cells, some of which contained perforin-positive granules. We found no evidence of human natural killer cells and noted occasional human, but not mouse, macrophages at a frequency indistinguishable from that resident in skin on animals not receiving human PBMCs. These human T cell infiltrates did not extend into adjacent mouse skin. Human immunoglobulin G antibody was detected in the blood and was diffusely present throughout mouse and human tissues in SCID mice receiving PBMCs. Mouse C3 was detected on human dermal vessels in both unreconstituted control animals and those that received PBMCs. Blood and tissues from mice injected with PBMCs depleted of B cells showed no human immunoglobulin, but circulating CD3+ cells were detected by flow cytometry at levels comparable with those of animals receiving whole PBMCs. Significantly, skin graft infiltration by human T cells and human dermal microvascular injury were equivalent in the B cell-depleted and whole-PBMC-reconstituted mice. Mice inoculated with PBMCs depleted of CD8+ T cells developed microvascular injury and infiltrates containing perforin-expressing CD4+ T cells. These data suggested a cytolytic T cell-dependent mechanism of microvessel injury. We then tested the ability of T cell immunosuppressants, cyclosporine and rapamycin, to attenuate vessel damage. Neither cyclosporine nor rapamycin alone effectively reduced either mononuclear cell infiltration or vascular injury. However, a combination of the two agents reduced both parameters. We conclude that the huPBL-SCID/skin allograft model may be used both to study cytolytic T cell-mediated rejection and to test the effect of immunosuppressive drug strategies in vivo in a small-animal model of human immune responses.     

T-cell abnormalities in inflammatory bowel disease are mediated by interleukin 2

Inflammatory bowel disease (IBD) may be an immunologically mediated disorder in which T cells are unable to respond appropriately to cell surface-associated antigens. To test this possibility, 37 patients with IBD, 24 with Crohn's disease and 13 with ulcerative colitis who were not being treated with immunosuppressive therapy were studied. The ability of T cells to proliferate in response to autologous or allogeneic cells, i.e., the autologous or allogeneic mixed-lymphocyte reaction (MLR) was tested. The autologous MLR was depressed using patient cells compared to control cells, regardless of disease type or activity (1564 +/- 223 cpm versus 3300 +/- 381 cpm, P less than 0.05) while the allogeneic MLR was depressed in patients with active disease only (29,833 +/- 2871 cpm versus 46,799 +/- 3340 cpm, P less than 0.01). The ability of T cells to recognize and lyse allogeneic cells, allogeneic cell-mediated lympholysis (CML), was also low in patients with active disease (24 +/- 4% versus 37 +/- 3%, P less than 0.05). Since T-cell proliferation and cytotoxicity depend upon adequate production of and response to a T-cell growth factor, interleukin 2 (IL-2), IL-2 production and responsiveness in IBD were studied. IL-2 production by patient T cells in response to phytohemagglutinin was only 39% of control values, P less than 0.05. The response to IL-2 was measured by the increase in T-cell proliferation in the autologous MLR in medium alone or medium supplemented with IL-2. Control T-cell proliferation rose from 3300 +/- 381 cpm to 10,761 +/- 428 cpm with exogenous IL-2 (P less than 0.001). Patient T-cell proliferation rose from 1564 +/- 223 cpm to 6817 +/- 771 cpm with IL-2 (P less than 0.001) but did not reach the level of the IL-2-supplemented control autologous MLR (P less than 0.05). In addition, the percentage of activated patient T cells having Tac antigen (IL-2 receptor) was depressed (P less than 0.05). These findings did not vary with disease type or activity. It is concluded from these data that peripheral blood T lymphocytes from patients with IBD have a diminished response to cell surface antigens which is associated with a decrease in IL-2 production and receptor generation. These defects may be responsible for the depressed T-cell proliferation and cytotoxicity that accompany IBD.     

Malignant B lymphocytes from non-Hodgkin's lymphoma induce allogeneic proliferative and cytotoxic T cell responses in primary mixed lymphocyte cultures: An important role of co-stimulatory molecules CD80 (B7-1) and CD86 (B7-2) in stimulation by tumor cells

We analyzed the stimulating capacities of malignant B cells from non-Hodgkin's lymphomas (NHL) to induce an allogeneic response in primary mixed lymphocyte reaction (MLR). T cells purified from a single healthy donor (KS) were used to compare the responses induced by either malignant or hyperplastic cells. Malignant B cells induced strong proliferation of KS cells independently of their level of expression of adhesion molecules. The KS cells after MLR were predominantly CD3⁺, CD25⁺, HLA-DR⁺, Ki67⁺ and CD45RO⁺ T cells, and the CD4/CD8 ratio was heterogeneous (from 0.8 to 2.7). To investigate the role of co-stimulatory molecules CD80 and CD86 for the stimulatory capacities of B cells, the expression of both molecules was analyzed before and during the MLR. Most fresh malignant B cells were negative for CD80 and CD86, whereas co-cultured B cells expressed high levels of both molecules. This expression was crucial for T cell proliferation, since monoclonal antibodies directed against CD80 and CD86 completely abrogated the MLR. We also report that KS responding cells at the end of co-culture were able to lyse fresh B cells used as stimulator cells to different extents (from 10 to 51%), and the level of lysis was enhanced after PMA activation of the target cells. Inhibition experiments using CD8 and CD4 mAb showed that effector cells were mainly CD8⁺. This report is the first to describe the accessory function of human malignant B cells from NHL and their sensitivity to lysis mediated by CD8⁺ T cells, and suggests new strategies for the development of antitumor immunity in NHL.