The effect of burn injury on CD8+ and CD4+ T cells in an irradiation model of homeostatic proliferation

BACKGROUND: Homeostatic proliferation of T cells has recently been shown to be an important mechanism in the host response to infection. However, its role in the T cell response to burn injury is unknown. In this study, we examine the effect of burn injury on CD4+ and CD8+ T cell homeostatic proliferation after irradiation. METHODS: Wild-type C57BL/6 female mice were irradiated with six grays ionizing radiation and 48 hours later, syngeneic whole splenocytes or purified CD4+ or CD8+ T cells labeled with carboxy-fluorescein diacetate, succinimidyl ester were adoptively transferred. Two days later, mice underwent a 20% burn injury, followed by splenocyte harvest 3 and 10 days after injury. RESULTS: Burn mice demonstrate increased splenic cellularity and CD8+ T cell proliferation after adoptive transfer of either purified CD8+ cells or whole spleen populations compared with unburned (sham) mice. In contrast, CD4+ T cell proliferation after burn injury is unchanged after adoptive transfer of whole spleen cells and drastically decreased after adoptive transfer of a purified CD4+ population compared with sham mice. Ten days after burn injury CD8+ T cells continue to demonstrate greater proliferation than CD4+ T cells. CONCLUSIONS: CD8+ T cells are more robust than CD4+ T cells in their proliferative response after burn injury. In addition, CD8+ T cell proliferation appears less reliant on other immune cells than purified CD4+ T cell proliferation. These data reiterate the importance of CD8+ T cells in the initial immune response to burn injury.     

Transition from T cell protection to T cell enhancement during tumor growth in an allogeneic host.

The cell-mediated immune response of mice toward a lethal allogeneic tumor was investigated during tumor development. The activity of spleen cells from the tumor-bearing mice was studied by transferring them together with 3LL tumor cells into normal C3H/eb recipient mice. The activity depended upon the time interval between inoculation of the tumor and transfer. Spleen cells taken relatively early, 1 week after tumor inoculation, mediated protection against tumor growth. In contrast, spleen cells taken 4 weeks after tumor inoculation markedly enhanced tumor growth. The tumor-enhancing cells, like the tumor-protecting cells, appeared to be T lymphocytes. The enhancing activity could be transferred by extra cellular medium prepared by incubating the enhancing T cells. Protecting activity could not be transferred by cell-free medium prepared from the protecting T cells. Both activities were found to exist to a relatively slight degree in populations of spleen cells from normal mice. The transition from T cell protection to T cell enhancement might be a determining factor in the outcome of the host-tumor relationship.     

Production of interferon-gamma by tumor-sensitized T cells is essential for interleukin-12-induced complete tumor eradication

BACKGROUND: Interferon-gamma (IFN-gamma) is essential for eradication of established large tumors by interleukin-12 (IL-12), but the critical source of IFN-gamma has not been defined. Adoptive transfer of T cells into T cell-deficient mice allows for evaluation of the role of T cells and T cell production of IFN-gamma in the antitumor immune response. METHODS: Wild-type C57BL/6, IL-12 receptor-beta1 knockout (IL-12Rbeta1 KO), IFN-gamma knockout (IFN-gamma KO), and IFN-gamma receptor-alpha knockout (IFN-gammaRalpha KO) mice were immunized and used as donors for adoptive transfer. Transfer of either splenocytes or CD90(+) T cells was performed into recipient T cell receptor-beta knockout (TCRbeta KO) and IFN-gamma/TCRbeta double knockout mice bearing 14-day subcutaneous MCA207 tumors. Half of the mice were treated with IL-12, and cure rates were compared. RESULTS: Transfer of either 1/4 immunized spleen equivalent or 10(7) immunized T cells into both TCRbeta KO and IFN-gamma/TCRbeta KO mice resulted in 80% to 100% cure when given with IL-12. However, transfer of 10(7) immunized T cells from IFN-gamma KO mice into TCRbeta KO mice was ineffective with or without IL-12. T cell response to IL-12, but not IFN-gamma, was required for tumor regression. CONCLUSIONS: Production of IFN-gamma by IL-12-responsive tumor-sensitized T cells is both necessary and sufficient for complete tumor eradication induced by IL-12. T cells are the source, but not the target, of IFN-gamma during tumor regression.     

Comparative immunohistologic studies in an adoptive transfer model of acute rat cardiac allograft rejection

It has been shown that fulminant acute rejection of rat cardiac allografts across a full haplotype disparity may occur as a direct result of adoptive transfer of sensitized W3/25+ MRC OX8- SIg- T helper/DTH syngeneic spleen cells to sublethally irradiated recipients. In order to establish the immunohistologic parameters of this form of rejection, allografts and recipient lymphoid tissue were analyzed using a panel of monoclonal antibodies of known cellular distribution. These data were compared with those obtained following reconstitution of irradiated allograft recipients with unseparated sensitized spleen cells, with unreconstituted irradiated donor recipient pairs, with unmodified first-set rejection, and with induced myocardial infarction of syngeneic heart grafts transplanted to normal and to sublethally irradiated recipients. Rejecting cardiac allografts transplanted to all reconstituted irradiated recipients were characterized by extensive infiltration with MRC OX8+ (T cytotoxic-suppressor, natural killer) cells even when this subset was virtually excluded from the reconstituting inocula. A similar proportional accumulation of MRC OX8+ cells observed at the infarct margins of syngeneic heart grafts transplanted to irradiated unreconstituted recipients greatly exceeded that present in normal nonirradiated controls. These data provide evidence that under conditions of heavy recipient irradiation, MRC OX8+ cells may be sequestered within heart grafts in response to nonspecific injury unrelated to the rejection process. Although there was no significant degree of MRC OX8+ cellular repopulation within organized secondary lymphoid tissues of irradiated animals over the study period, the density of ileal mucosal MRC OX8+ lymphocytes approximated normal at 7 days post-irradiation, raising the possibility that these cells could share a common origin with those sequestered within the heart grafts. Carbon+ MRC OX6+ macrophages were a significant component of the infiltrate in all rejecting cardiac allografts, as well as in all infarcted syngeneic heart grafts--providing further evidence that macrophage "activation" with expression of class II determinants may occur in response to nonspecific injury. In unmodified first-set rejection there was an intense B cell reaction in recipient spleens and lymph nodes. In the adoptive transfer model, marked B cell expansion was exclusively confined to the parathymic lymph nodes of irradiated allograft recipients reconstituted with the sensitized W3/25+, MRC OX8-, SIg- T helper/DTH donor cell inocula.(ABSTRACT TRUNCATED AT 400 WORDS)     

Antitumor activity against established intracerebral gliomas exhibited by cytotoxic T lymphocytes, but not by lymphokine-activated killer cells.

Specific immune responses against malignant brain tumors have been difficult to demonstrate. Moreover, immunotherapy has met with little success, despite using lymphocytes with high levels of cytotoxicity against brain tumor cells. Lymphokine-activated killer (LAK) cells that nonspecifically kill brain tumor cells are produced by stimulating resting precursors with high concentrations of interleukin-2 (IL-2). Cytotoxic T lymphocytes that specifically kill brain tumor cells are produced by stimulating antigen receptor-positive immune-cell precursors with tumor cells. In an attempt to gain insight into immune cell function against brain tumors, the present study compared the in vitro and in vivo activities of LAK cells and cytotoxic T lymphocytes produced against RT2, a fast-growing rat glioma cell line. Lymphokine-activated killer cells were produced by stimulating normal rat spleen cells with 1000 units of IL-2, and RT2-specific cytotoxic T lymphocytes were produced by priming them in vivo with RT2 and Corynebacterium parvum and restimulating primed spleen cells with RT2 in vitro. Lymphokine-activated killer cells were highly cytotoxic for a panel of syngeneic and allogeneic brain tumor and non-brain tumor target cells, including RT2, as measured in a 4-hour 51Cr release assay. Cytotoxic T lymphocytes were highly cytotoxic only for syngeneic brain tumor target cells. Lymphokine-activated killer cells and cytotoxic T lymphocytes were tested for in vivo antitumor activity against intracerebral RT2 by intravenous adoptive transfer of activated lymphocytes. Untreated rats died in approximately 2 weeks. Lymphokine-activated killer cells plus IL-2 failed to affect survival when treatment was initiated as early as 1 day following tumor inoculation. Cytotoxic T lymphocytes and IL-2 administered as late as Day 5 rejected progressing intracerebral tumor. Thus, although both cytotoxic T lymphocytes and LAK cells exhibited high levels of in vitro killing of glioma cells, only cytotoxic T lymphocytes rejected progressing intracerebral tumors.     

Immunobiology of xenogeneic cornea grafts in mouse eyes. II. Immunogenicity of xenogeneic cornea tissue grafts implanted in anterior chamber of mouse eyes

BACKGROUND: Xenogeneic corneal fragments (guinea pig) are highly resistant to immune rejection in the anterior chamber of mouse eyes. Because guinea pigs and mice are discordant (i.e., mouse serum normally contains guinea pig reactive xenoantibodies), we wished to determine the extent to which xenogeneic corneal fragments placed intraocularly in normal and specifically sensitized mice activated xenoreactive T and B cells. METHODS: Guinea pig corneas, deprived surgically of epithelium, were cut into fragments and inserted into the anterior chamber of eyes of BALB/c mice, adjacent to the central cornea of the recipient. Antibody (immunoglobulin [Ig]M, IgG) and delayed type hypersensitivity (DTH) immune responses of recipient mice to guinea pig xenoantigens were assessed. The fate of xenogeneic cornea implants was assessed in mice immunized systemically to guinea pig antigens. RESULTS: Guinea pig spleen cells and corneal fragments implanted s.c. induced within 2 weeks of immunization both DTH and IgG antibodies to guinea pig xenoantigens. By contrast, xenogeneic corneal fragments implanted in the anterior chamber of mouse eyes evoked no change in recipient humoral immune status and induced mild guinea pig-specific DTH only after 5 weeks. Presensitization of mice to guinea pig xenoantigens failed to increase the proportion of grafts that were regarded as rejected, but the onset of rejection in failed grafts occurred earlier than in unsensitized recipients. Active systemic immunization of mice bearing intracameral guinea pig corneal fragments failed to curtail the grafts' survival. Guinea pig corneal fragments implanted in the anterior chamber of normal mice failed to induce anterior chamber-associated immune deviation. CONCLUSIONS: Xenogeneic corneal fragments implanted in the anterior chamber of eyes of normal mice display strikingly reduced immunogenicity, and an inability to induce anterior chamber-associated immune deviation. These properties are discussed in terms of the vulnerability of guinea pig corneal tissue to immune rejection within the eye.     

Impaired immune response by isoniazid treatment during intravesical BCG administration in the guinea pig.

At present, isoniazid (INH) is being used prophylactically to reduce the side effects of intravesical BCG therapy for superficial bladder cancer, although it is not clear whether or not this reduces the antitumor efficacy of BCG. In this study the impact of INH treatment on the immune response after repeated intravesical BCG administration was investigated in guinea pigs. INH was given on the 3 days around each BCG instillation. We found that the administration of INH severely impaired the immunological effects of BCG. The induction of mononuclear cell infiltration in the bladder wall was reduced. Enlargement of the regional lymph nodes (weight and number of cells), and increase of MHC Class II expression on the lymph node cells, normally observed after intravesical BCG administration, were inhibited by INH. Systemic immunity, measured by the DTH reaction in the skin to PPD, was also diminished due to the combined treatment of BCG with INH. When INH was administered during the last 4 of 6 BCG instillations, the immune response to BCG was still impaired. A five-fold increase of the dose of BCG did not overcome the effect of INH. INH probably did not exert a direct suppression of the immune system of the guinea pig as the DNCB skin reactivity was not influenced. Although INH concentrations in the urine were high at the onset of the instillation, in vitro experiments indicated that the effect of INH may not be caused by killing of the BCG organisms shortly after application in the bladder. In conclusion, our data in guinea pigs suggest that the use of INH may impair the immune response to intravesical BCG. As this response may be important for the antitumor effect of BCG, urologists should be cautious with the prophylactic use of INH. The influence on the antitumor efficacy is now investigated in man.     

Inhibition of Host Signal Transducer and Activator of Transcription Factor 6 Results in Cure With Cyclophosphamide and Interleukin 12 Immunotherapy

BACKGROUND: Interleukin (IL)-12 immunotherapy is highly effective against established immunogenic tumors. However, nonimmunogenic tumors fail to respond to IL-12 therapy. Analysis of tumor rejection of the immunogenic tumors shows that a preexisting antitumor immune response is required for an effective IL-12 response. It is not known whether this lack of a preexisting host antitumor immune response is a limiting factor for the lack of response to IL-12 therapy by nonimmunogenic tumors. METHODS: Experiments were done using the spontaneously arising nonimmunogenic metastatic murine breast 4T1 carcinoma in normal and STAT6 knockout BALB/c mice. RESULTS: 4T1 is nonimmunogenic in normal mice, and established subcutaneous tumors are resistant to immunotherapy with cyclophosphamide (Cy) plus IL-12. However, in STAT6 knockout mice, 4T1 becomes immunogenic, and established 4T1 tumors are eradicated by Cy plus IL-12. Adoptive transfer of spleen cells from normal mice into STAT6 knockout mice before tumor inoculation reduces both the immunogenicity and response to Cy plus IL-12 immunotherapy of 4T1 in the recipient mice. CONCLUSIONS: Cy plus IL-12 immunotherapy can eradicate nonimmunogenic tumors as long as a preexisting immunity is established in the tumor-bearing host. Furthermore, the STAT6 pathway is likely involved in the suppression of the development of host antitumor immunity.     

Prospects for cellular immunotherapy for metastatic melanoma.

Systemic therapy for metastatic malignant melanoma has been disappointing. The search for alternate therapeutic methods includes investigation of the interaction between melanoma and the human immune system. A cellular immune response to melanoma has been documented in vitro and in vivo. In most patients with disseminated disease, however, immune T cells fail to eradicate the tumor. While this phenomenon is poorly understood, the occasional occurrence of spontaneous regression provides some indication that the immune response may, in fact, be capable of eradicating established tumor in vivo. Current efforts to augment and to direct the immune response to melanoma include investigation of specific and nonspecific adoptive immunotherapy. Specific therapy includes the generation of tumor-activated specific killer cells from peripheral blood, draining nodes, or metastatic tumor deposits. An increasing understanding of antigen recognition and improved methodology for T-cell culture are contributing toward the application of cellular immunotherapy to patients with melanoma.     

Adoptive Transfer of Tracer‐Alloreactive CD4+ T Cell Receptor Transgenic T Cells Alters the Endogenous Immune Response to an Allograft

T cell receptor transgenic (TCR‐Tg) T cells are often used as tracer populations of antigen‐specific responses to extrapolate findings to endogenous T cells. The extent to which TCR‐Tg T cells behave purely as tracer cells or modify the endogenous immune response is not clear. To test the impact of TCR‐Tg T cell transfer on endogenous alloimmunity, recipient mice were seeded with CD4⁺ or CD8⁺ TCR‐Tg or polyclonal T cells at the time of cardiac allograft transplantation. Only CD4⁺ TCR‐Tg T cells accelerated rejection and, unexpectedly, led to a dose‐dependent decrease in both transferred and endogenous T cells infiltrating the graft. In contrast, recipients of CD4⁺ TCR‐Tg T cells exhibited enhanced endogenous donor‐specific CD8⁺ T cell activation in the spleen and accelerated alloantibody production. Introduction of CD4⁺ TCR‐Tg T cells also perturbed the intragraft accumulation of innate cell populations. Transferred CD4⁺ TCR‐Tg T cells alter many aspects of endogenous alloimmunity, suggesting that caution should be used when interpreting experiments using these adoptively transferred cells because the overall nature of allograft rejection may be altered. These results also may have implications for adoptive CD4⁺ T cell immunotherapy in tumor and infectious clinical settings because cell infusion may have additional effects on natural immune responses.     

The nonessential role of a humoral antibody response in acute rat cardiac allograft rejection. An ultrastructural tracer study in an adoptive transfer model

Progressive microvascular endothelial damage is a characteristic feature of fulminant acute cardiac allograft rejection in the rat. Serial ultrastructural tracer studies using i.v. administered colloidal carbon and horseradish peroxidase have been performed in an adoptive transfer model to determine the role of cellular and humoral immune mechanisms in the pathogenesis of endothelial injury in this setting. Sublethally irradiated (780 rads) Lewis recipients of Wistar-Furth cardiac allografts reconstituted with unfractionated syngeneic immune spleen cells (2 X 10(7)] or with inocula depleted of SIg+ cells (1 X 10(7)] were studied at days 5-7 posttransplantation, and the ultrastructural tracer data were correlated with recipient alloantibody titers. The progression of microcirculatory endothelial damage within rejecting cardiac allografts was similar when recipients were reconstituted with unfractionated immune spleen cells or with SIg- cells, and the serial changes present were comparable to those documented in unmodified first-set rejection in this strain combination. Unreconstituted controls showed no apparent microvascular alterations. A significant alloantibody response was confined to recipients reconstituted with unfractionated immune spleen cells. All unreconstituted recipients and recipients that received splenic inocula depleted of SIg+ cells (SIg-) lacked detectable antibody in the study period. These results indicate that a humoral antibody response is not essential for induction of endothelial damage in fulminant acute rejection of rat cardiac allografts.     

Surgery, trauma and immune suppression. Evolving the mechanism.

A major surgical procedure can impair the delayed hypersensitivity response. This impairment is associated with suppressor cell activity that can alter either afferent or efferent responses. Using the third party mixed leukocyte culture to define cell types involved, major immune impairment was seen with the combination of both nonadherent and plastic adherent cells, suggesting that a T cell-macrophage interaction is required. A serum factor(s) is present in operated mice that can impair mixed leukocyte culture reactivity. A serum factor(s) in an adoptive transfer experiment is also capable of enhancing primary tumor growth. A unifying hypothesis, based predominantly on data from the current literature, is presented in an attempt to elucidate the mechanism by which all forms of major trauma are associated in some patients with "paradoxical" immune suppression.     

Immune response to ultraviolet-induced tumors. II. Effector cells in tumor immunity

Skin tumors induced in mice by chronic ultraviolet irradiation are highly antigenic and can induce a state of transplantation immunity in syngeneic hosts. In the present study, we compared the in vitro cytolytic activity of splenic lymphocytes from mice immunized with either a regressor or a progressor UV-tumor. The results of this comparison supported previous work implicating a role for tumor-specific cytolytic T lymphocytes in the rejection of regressor UV-tumors. The results also revealed that immunization with the progressor UV-tumor 2237 failed to elicit detectable levels of progressor tumor-specific CTL in animals capable of rejecting the immunizing tumor. Interestingly, following in vitro resensitization of both regressor and progressor immune spleen cells, we found a previously undetected lymphocyte population with anti-UV-tumor activity. Besides lysing UV-tumors in vitro, these lymphocytes also lysed a wide variety of additional tumor targets. This effector activity along with the analysis of cell surface markers indicated that these lymphocytes belong to that category of effector cells mediating natural-cell-mediated cytotoxicity (NCMC). As we had not detected cells with this activity in splenic lymphocyte preparations prior to in vitro resensitization, we examined lymphocytes from the local tumor environment during the course of progressor 2237 tumor rejection for either NCMC activity or tumor-specific CTL activity. This in situ analysis revealed lymphocytes exhibiting significant levels of cytolytic activity against several UV-tumors, thus implicating NK cells as effector cells in the rejection of progressor UV-tumors by immune animals. The mechanisms whereby NK cells with NCMC activity could be induced in immune animals are discussed in the context of class-II-restricted immune responses by helper/inducer T lymphocytes.     

T-cell-mediated rejection of vascularized xenografts in the absence of induced anti-donor antibody response.

T cells are considered to play a major indirect role in the pathogenesis of xenograft vascular rejection, by promoting the induction of anti-donor antibodies that trigger complement- and antibody-dependent cell cytotoxicity. However, how vigorous the T cell xenoresponse is in vivo, and whether, besides their helper function, T cells are capable of directly affecting the graft is still unclear. We have previously shown that cyclosporine A (CsA) withdrawal in accommodated cardiac xenograft recipient allows for a rapid and dense T-cell infiltration, concomitant to an acute graft rejection. In this paper we further characterize the role of T cells in this rejection process and we demonstrate that adoptive transfer of CD4+ T cells in irradiated recipients of long-term cardiac xenografts is sufficient to trigger acute rejection, in the absence of any detectable induced anti-hamster antibody response. Therefore, our data suggest that unusually strong T-cell response will be another major barrier to xenotransplantation, even if antibody-mediated vascular rejection is controlled.     

A cytotoxic T-lymphocyte clone derived from mice with progressively growing tumors.

Tumor-specific T-cell clones were derived from spleen cells of mice bearing a syngeneic PHS-5 tumor (a P815 mastocytoma mutant). Cells were expanded in vitro and characterized and assayed for activity against the relevant tumor in vivo. Clone cells were CD4-, CD8+ T lymphocytes, as determined by fluorescence activated cell sorting analysis and were specifically cytotoxic against P815 tumor cells in vitro, as shown in chromium 51 release assays. These cells require both antigen and interleukin 2 to proliferate; neither alone is sufficient, even with the addition of interleukin 1. In an experimental P815 liver metastasis model, the adoptive transfer of GD11 or GD11.17 clone cells and injection of recombinant interleukin 2 (7500 U intraperitoneally) 3 days after infusion of tumor cells reduced the number of tumor nodules, while the adoptive transfer of lymphokine-activated killer cells was ineffective.     

Allografts Stimulate Cross‐Reactive Virus‐Specific Memory CD8 T Cells with Private Specificity

Viral infections have been associated with the rejection of transplanted allografts in humans and mice, and the induction of tolerance to allogeneic tissues in mice is abrogated by an ongoing viral infection and inhibited in virus‐immune mice. One proposed mechanism for this ‘heterologous immunity’ is the induction of alloreactive T cell responses that cross‐react with virus‐derived antigens. These cross‐reactive CD8 T cells are generated during acute viral infection and survive into memory, but their ability to partake in the immune response to allografts in vivo is not known. We show here that cross‐reactive, virus‐specific memory CD8 T cells from mice infected with LCMV proliferated in response to allografts. CD8 T cells specific to several LCMV epitopes proliferated in response to alloantigens, with the magnitude and hierarchy of epitope‐specific responses varying with the private specificities of the host memory T cell repertoire, as shown by adoptive transfer studies. Last, we show that purified LCMV‐specific CD8 T cells rejected skin allografts in SCID mice. These findings therefore implicate a potential role for heterologous immunity in virus‐induced allograft rejection.     

Expression level of costimulatory receptor ICOS is critical for determining the polarization of helper T cell function

We found that inducible costimulator (ICOS)-deficient spleen cells have a defect in the ability to induce Th2-mediated chronic graft-versus-host disease (GVHD), whereas they were fully capable of inducing Th1-mediated acute GVHD. In contrast, CD28-deficient spleen cells induced neither acute nor chronic GVHD. To define the mechanisms of how these two CD28 family molecules manifest distinct functions in GVHD, the kinetics of their surface expression by donor T cells in two types of GVHD were investigated. It was found that expression of ICOS by donor T cells dramatically up-regulated after adoptive transfer in both acute and chronic GVHD, but in acute GVHD this up-regulation was transient and quickly down-regulated. In contrast, donor T cells in chronic GVHD maintained high levels of ICOS expression throughout the experiment. These results suggested that ICOS-mediated costimulatory signals are predominantly active in Th2-dominant responses. Changing patterns of CD28 expression by donor T cell were identical in both GVHD as they exhibited slight but sustained up-regulation after transfer, suggesting that CD28 provides a costimulatory signal necessary for the initial T cell activation, regardless of whether in Th1 or Th2 responses. These results lead us to propose that the expression levels of costimulatory receptors are critical for determining the polarization of helper T cell function.     

混合培养的供、受者骨髓细胞过继回输延长小鼠移植心脏存活时间

目的 将供、受者骨髓细胞经混合培养后过继回输,以观察其对同种异体移植心脏存活时间和受者免疫功能的影响.方法 取Balb/c小鼠和C57BL/6J小鼠的骨髓细胞,进行混合培养.配制含Balb/c小鼠和C57BL/6J小鼠脾淋巴细胞的混合淋巴细胞反应体系(MLR)以及含Balb/c小鼠和C3H小鼠脾淋巴细胞的MLR,分别加入混合培养的骨髓细胞,观察其对MLR中细胞增殖的影响.以C57BL/6J小鼠为供者,Balb/c小鼠为受者行腹腔异位心脏移植,实验分为4组:(1)移植对照组,受者仅进行心脏移植,不作其他处理;(2)实验对照组,心脏移植后给予西罗莫司灌胃;(3)实验组,移植手术结束前注射混合培养的骨髓细胞1×10~7个,术后给予西罗莫司;(4)第三方对照组,受者接受C3H小鼠的移植心脏,手术结束前注射混合培养的骨髓细胞1×10~7个,术后给予西罗莫司.记录移植心脏存活时间;移植心脏停跳当日,取受者外周血,检测CD4~+ CD25~+ T淋巴细胞的比例及供者来源的H-2K~b细胞的比例.结果 加入混合培养的骨髓细胞后,Balb/c和C57BL/6J的MLR的淋巴细胞增殖率低于Balb/c和C3H的MLR.实验组移植心脏的存活时间长于其他3组(P<0.05).实验组CD4~+CD25~+T淋巴细胞的百分率高于其他3组(P<0.05).实验组外周血中H-2K~b细胞的比例高于其他3组(P<0.05).结论 受者输注混合培养的供、受者骨髓细胞可在一定程度上调节免疫应答,延长小鼠移植心脏的存活时间,该作用具有供者抗原特异性.     

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.     

Induction of hyperacute rejection of skin allografts by CD8+ lymphocytes

BACKGROUND: Second-set rejection is generally regarded as a phenomenon mainly mediated by humoral cytotoxic antibodies, although a few discordant data have been presented. In the reported experiments, we have taken advantage of the absence of production of specific cytotoxic alloantibodies contrasting with the normal development of transplantation cellular immunity, in two murine models: chimeric mice and RAG mice. METHODS: Chimeras (BALB/c-->CBA) were obtained by transplantation of 2x10(7) fetal liver cells from BALB/c (H-2d) mice to lethally irradiated CBA (H-2k) mice. After hyperimmunization with third-party C57/ BL6 (B6) (H-2b) skin transplants and with injections of 2x10(7) B6 spleen cells, antibody production, and skin graft survival were analyzed. To identify further the factors or cells responsible for accelerated rejection of B6 skin transplants in hyperimmunized chimeras, transfer experiments were carried out involving the injection of serum, whole spleen cells, spleen T cells, spleen CD8+ T cells or spleen CD4+ T cells from chimeras into BALB/c mice that had received 6 Gy irradiation. The recipient mice were then grafted with B6 skin. Similarly, the immunodeficient RAG mice were used to construct a model of recipient animals with anti-H-2d hyperimmunized B6 T cells in the total absence of antibody. RESULTS: In chimeras, anti-B6 cytotoxic antibodies were not detectable in any of hyperimmunized chimeric mice, yet accelerated rejection of B6 skin transplant occurred: a graft survival of 8.6+/-0.5 days (d), comparable to 8.9+/-0.8 d survival in CBA control mice subjected to the same hyperimmunization procedure, and significantly shorter than that in nonhyperimmunized (BALB/c-->CBA) chimeras (11.6+/-0.5 d) or in non-hyperimmunized CBA control mice (12.1+/-0.6 d). High titers of anti-B6 cytotoxic antibodies were present in the serum of hyperimmunized CBA control mice. In transfer experiments, the graft survival was over 14 d in mice treated with irradiation alone, with irradiation + serum or with irradiation + CD4+ T cells. It was significantly shorter in mice treated with irradiation + whole spleen cells, with irradiation + T cells or with irradiation + CD8+ T cells (8.9+/-0.8 d). Similarly, in immunodeficient RAG mice, reconstitution of the T cell compartment with T cells from hyperimmunized B6 mice led to accelerated rejection of BALB/c skin allografts (11.4+/-1.1 d vs. 18.8+/-0.8 d when T cells were provided by nonimmunized mice). In a second transfer of cells from these reconstituted RAG mice into naive RAG mice, CD8+ T cells were shown to induce accelerated rejection of skin allografts (12.0+/-0.6 d) whereas CD4+ T cells were much less efficient (16.5+/-0.1 d). CONCLUSION: These data indicate that T cells, and especially the CD8+ subset, can be responsible for second-set rejection in the absence of anti-donor antibodies in chimeric and RAG mouse models. These sensitized CD8+ T cells are also likely to play an important role in normal mice, in addition to that of cytotoxic antibodies.