Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018133 (graft-versus-host disease)
 18,032 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An adult recipient of an HLA-DR, DQ-mismatched, T cell-depleted bone marrow graft, who remains without graft versus host disease and who is not maintained on immunosuppressive therapy, was studied at 23 months posttransplantation for in vitro reactivity against the mismatched antigens of the host. The donor's PBMC's proliferated vigorously against the recipient's stimulators in the pretransplant mixed lymphocyte cultures (MLC). After transplant reconstitution, MLCs demonstrated that the in vitro response of engrafted donor T cells against host MHC class II antigens was equivalent to control allogeneic responses, while there was no detectable response against the donor's antigens. Posttransplantation limiting dilution analysis showed no difference between the precursor frequencies of antihost responders among populations of fresh donor PBMCs and among the engrafted cells of donor origin that are found circulating in the patient. This result suggests that clonal deletion is, at best, incomplete and that peripheral tolerance is essential in protecting this patient from GVHD. These findings also support the conclusion that bone marrow-derived thymic elements may be important for clonal deletion in human chimeras.
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PMID:In vitro alloreactivity against host antigens in an adult HLA-mismatched bone marrow transplant recipient despite in vivo host tolerance. 842 68

Clinical trials and experimental studies have demonstrated that donor T cells can play a critical role in preventing allogeneic marrow graft rejection. Results of a previous study showed that donor T cells were most effective for preventing rejection when they recognize an alloantigen expressed by recipient T cells and can cause graft-versus-host disease (GVHD). The present study examined models where marrow graft rejection can be prevented by donor T cells that do not recognize host alloantigens and cannot cause GVHD. Donor T cells prevented rejection of major histocompatibility complex (MHC) class I and II-disparate F1 marrow in parental recipients prepared with > or = 800 cGy total body irradiation (TBI) but not in those prepared with < or = 750 cGy TBI. In recipients prepared with high TBI exposures, rejection was mediated entirely by host CD8 cells. With lower TBI exposures, rejection was mediated by host CD4 cells and CD8 cells. These observations suggested the hypothesis that donor T cells prevent rejection mediated by host effectors that recognize donor MHC class I alloantigens but do not prevent rejection mediated by host effectors that recognize donor class II alloantigens. Consistent with this hypothesis, further experiments showed that F1 donor T cells can prevent rejection of MHC class I-disparate marrow in irradiated parental recipients but have no detectable effect on rejection of MHC class II-disparate marrow. We propose that the expression of MHC class I molecules on donor T cells makes it possible for these cells to inactivate the host response against donor class I alloantigens through a veto mechanism, whereas the absence of MHC class II molecules on murine T cells explains why these cells cannot inactivate the host response against donor class II alloantigens. Finally, donor CD4 cells and CD8 cells were equivalently effective for preventing rejection of F1 marrow in parental recipients, suggesting that veto activity is not restricted solely to the CD8 subset of murine T cells. A veto mechanism could enable donor T cells to prevent allogeneic marrow graft rejection without causing GVHD.
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PMID:Prevention of allogeneic marrow graft rejection by donor T cells that do not recognize recipient alloantigens: potential role of a veto mechanism. 870 55

Immunohistochemical examination of rat skeletal muscle during graft-versus-host disease (GVHD), a systemic immune reaction, was performed to investigate specific immune reactivities focusing on major histocompatibility complex (MHC) expression and inflammatory cell infiltration of skeletal muscle during a systemic immune reaction. MHC class II expression and inflammatory cell infiltration did not increase. MHC class I was expressed along the contour of muscle fibres, and most strongly expressed by the cells which were distributed throughout the endomysium and perimysium. Seventy-six percent of these MHC class I+ cells carried endothelial cell-markers, while 24% of them did not. The latter cells were revealed not to be inflammatory cells such as lymphocytes, granulocytes or macrophages when examined by immunostaining using several exudate-cell markers. Neither were they myosatellite cells because they were located outside the basement membrane. These results may be useful for considering animal models of inflammatory myopathies such as polymyositis and dermatomyositis.
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PMID:Major histocompatibility complex expression in muscle of rats with graft-versus-host disease. 872 Apr 52

Hydroxychloroquine (HCQ) interferes with antigen processing and with receptor loading and recycling by raising the pH of lysosomes and endosomes. HCQ thus inhibits MHC class II-restricted antigen presentation by blocking the binding of peptides to MHC molecules. Additionally, HCQ has been shown to diminish the release of several cytokines. In light of these mechanisms of action, we felt that HCQ might be useful in the bone marrow transplant setting and therefore investigated its effect on alloreactivity in vitro. We have demonstrated that HCQ causes a dose-dependent reduction of the cytotoxicity, proliferation, and TNF alpha production resulting from allorecognition in mixed lymphocyte culture (MLC). HCQ does not mediate its effect solely through antigen processing and presentation and other early events since addition of HCQ as late as 120 h after the initiation of the MLC still has a suppressive effect on cytotoxicity. HCQ also inhibits the cytotoxicity of previously primed effectors. These results support an effect of HCQ on terminal mechanisms of cytotoxicity that have not been previously reported. HCQ's ability to reduce the cytotoxicity, proliferation, and TNF alpha production resulting from allorecognition suggests that it may be useful in the prevention and treatment of graft-versus-host disease (GVHD).
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PMID:The effect of hydroxychloroquine on alloreactivity and its potential use for graft-versus-host disease. 880 16

Previously, it has been shown that the lysosomotropic amine, chloroquine, is effective in the prevention of graft-versus-host disease (GVHD) using murine models. Because chloroquine and hydroxychloroquine suppress MHC class II antigen presentation, their mechanism of action is different to other immune suppressant drugs (cyclosporin A) currently used to control GVHD. It is possible that the use of cyclosporin A and chloroquine in combination may have an additive or synergistic effect on T cell responses to antigens presented in the context of MHC class II. We investigated the effects of chloroquine or hydroxychloroquine in combination with cyclosporin A on human T cell responses in vitro to tetanus toxoid, an exogenous protein antigen dependent on MHC class II presentation for proliferative responses. We demonstrate that similar levels of chloroquine and hydroxychloroquine suppress human T cell responses to tetanus toxoid and that the use of either agent in combination with cyclosporin A results in synergistic suppression. Evaluation for a direct effect by the lysosomotropic amines on T cells, in the absence of antigen presenting cells, revealed that there was inhibition of T cell responses but only at high concentrations. No significant decrease or increase was seen in surface MHC II or invariant chain expression or in cytoplasmic invariant chain after exposure to chloroquine. Thus, lysosomotropic amines in combination with cyclosporin A are synergistic in suppression of T cell proliferation. Use of these agents in combination with cyclosporin A may improve control of graft-versus-host disease.
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PMID:Synergy between lysosomotropic amines and cyclosporin A on human T cell responses to an exogenous protein antigen, tetanus toxoid. 887 28

The goal in tissue transplantation is the restoration of all natural (physiological) communication pathways between the host and the graft. To this end, the effects of microsurgical reconstruction of artery, vein, lymphatic vessel, and nerve during grafting were investigated. Allogenic (MHC class II incompatible) and isogenic orthotopic (graft in functional continuity) small bowel recipients with immediate microsurgical lymphatic and nerve anastomosis were observed clinically as well as by immunological and histological examination. To explain the influence of the lymphatic system in allograft survival, short-term therapy was applied with the immunosuppressant cyclosporin A (10 mg/kg i.m.) for only 5 postoperative days. Average allograft survival ended in the control group after 10 days without any therapy, increased up to 20 days after immunosuppressive therapy (in both groups acute rejection and graft-versus-host disease were seen) and increased further to more than 200 days following lymphatic connection of the host and the graft during allografting. In this group no lymphatic edema of the graft was seen. To determine the optimal location of nerve anastomoses between the host and the graft without irritating the host nerve system, isografts in the same model were investigated. No paralysis of graft neighboring tissues was seen when the last ganglion function, and its following nerve plexus, of the host is saved. Nerve reconstruction must be undertaken after this last crossing of regional nerve fibers before entering the organ. The same rule is effective for organ explantation.
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PMID:Microsurgical reconstruction of the lymphatic and nerve system in small bowel transplantation: the rat model, first results. 895 47

Bile duct cells (BDCs), especially intrahepatic cholangiocytes, are primary targets of immune-related injury in such pathologic processes as liver graft rejection, liver graft-versus-host disease, and primary sclerosing cholangitis. Cholestasis and progressive loss of intrahepatic BDCs indicate chronicity in these diseases. The present investigation characterizes the acquisition of immune markers of intrahepatic BDCs isolated from mice after bile duct ligation. Purified BDCs from cholestatic C57BL/6 (H-2b) mice express not only the major histocompatibility complex (MHC) class I and class II antigens but also the costimulatory molecules B7-1 (CD80) and B7-2 (CD86). The expression of the MHC class II molecules on BDCs before and after interferon (IFN)-gamma exposure is also demonstrated by immunohistochemistry on the cultured cells. Cytotoxicity assays indicate the vulnerability of these cells as targets for immunologic injuries. Effector cells generated from B10.BR splenocytes (H-2k) against C57BL/6 splenocytes (H-2b) show comparable killing of BDCs and EL4 cells, the latter being a lymphoma line that was established from the C57BL/6N (H-2b) mouse. An immortalized mouse BDC line (IBDC) is included in this study to validate some of the findings from BDCs isolated from bile duct-ligated mice. We suggest that cholestatic BDCs express surface antigens different from those of normal epithelial cells that result in increased susceptibility to damage by immune mechanisms.
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PMID:Phenotypical and functional characterization of intrahepatic bile duct cells from common duct ligated mice. 896 Jun 34

Despite improved procedures in chemotherapy and bone marrow transplantation (BMT), post-BMT leukemia relapse rates have remained rather constant in the last decade. Immunotherapy with monoclonal or bispecific antibodies (bsAb) is a promising approach to improve this situation, but is hampered by the absence of tumor-specific antigens on the majority of tumors. To evade this problem, we developed a new tumor-specific approach in which bispecific antibodies exploit chimerism after allogeneic BMT by redirecting donor T cells against recipient-specific antigens on tumor cells. Two different leukemia relapse models were established using a T-cell lymphoma (ST-1) and a B-cell lymphoma (BCL1) to evaluate the efficiency of such a therapy. In these experiments, irradiated BALB/c (Thy-1.2+, I-Ad) mice were transplanted with C57BL/6 Thy-1.1 (I-Ab) BM cells under the protection of graft-versus-host disease-preventing monoclonal antibodies. Forty-five days after BMT, the chimeric mice were injected with either 2 x 10(4) recipient-type, Thy-1.2+, CD3- ST-1 cells or major histocompatability complex (MHC) class II+ (I-Ad)-BCL1 cells. Four days later, the mice were treated with 8 microg bsAb G2 (anti-CD3 x anti-Thy-1.2) or 10 microg (+10 microg, day 6) bsAb BiC (anti-CD3 x anti-I-Ad), respectively. These combinations guaranteed exclusive binding of the bsAbs target arms to tumor cells, leaving the surrounding, donor-type hematopoietic cells unbound. Compared with the parental antibodies, the bsAbs markedly reduced tumor mortality. Between 34% and 83% of mice survived in the bsAb groups compared with 0% of the control groups treated with parental antibodies, clearly documenting the benefit of the redirection principle. Furthermore, cytokine release (interleukin-6) after anti-CD3 antibody or bsAb treatment was decreased by administering a low-dose antibody preinjection. We have shown (1) that 6 weeks after BMT, when donor T-cell reconstitution is still in progress, T-cell-redirecting bsAb are clearly superior to parental antibodies in terms of tumor cell elimination; and (2) that the polymorphism of a common antigen such as Thy-1 or a clinically more relevant target antigen such as MHC class II can be used as an operational tumor-specific antigen after allogeneic BMT.
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PMID:Bispecific antibodies target operationally tumor-specific antigens in two leukemia relapse models. 897 58

Administration of the immunosuppressive drug cyclosporine after autologous bone marrow transplantation induces a systemic autoimmune syndrome resembling graft-versus-host disease (GVHD). This syndrome termed autologous GVHD has significant antitumor activity. Associated with autologous GVHD is the development of T lymphocytes that recognize major histocompatibility complex (MHC) class II determinants, including self. The present studies attempted to characterize and define the molecular specificity of the effector T lymphocytes in autologous GVHD induced in patients with metastatic breast cancer. The results suggest that the effector cells associated with human autologous GVHD are CD8+ T lymphocytes expressing the alpha/beta T-cell receptor. Additional studies show that the effector T cells recognize MHC class II antigens in association with a peptide from the invariant chain (CLIP). Pretreatment of autologous lymphoblast target cells with anti-CLIP antibody completely blocked lysis mediated by autologous GVHD effector T cells. On the other hand, force loading this peptide markedly enhanced the susceptibility of the target cells to recognition by the autoreactive T cells. The recognition of the MHC class II CLIP complex may account for the novel specificity of the effector T cells associated with human autologous GVHD. Moreover, identification of the target peptide may allow for the development of novel immunotherapeutic strategies to enhance the antitumor efficacy of autologous GVHD.
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PMID:Specificity of effector T lymphocytes in autologous graft-versus-host disease: role of the major histocompatibility complex class II invariant chain peptide. 905 45

Treatment with cyclosporine A, a prototypic immunosuppressive drug, following autologous bone marrow transplantation (autoBMT) induces autologous graft-versus-host disease (autoGvHD), similar to acute GvHD after allogeneic BMT. The development of autoGvHD appears to be associated with the emergence of autoreactive T cells recognizing self MHC class II antigens and the elimination of a T-cell-dependent peripheral autoregulatory mechanism. The induction of autoGvHD may be of benefit to the autoBMT patients by providing the graft-versus-tumor effect.
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PMID:Autologous graft-versus-host disease. 907 14


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