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)

Major histocompatibility complex antigens are critical to an animal's immune response. In most animals, the extreme polymorphism of MHC molecules complicates studies of the role of this complex in the immune response. In mice, however, MHC haplotype-homozygous inbred strains have been developed which are invaluable in the study of the immune system and the search for immune response genes. The human MHC bears many similarities to its murine equivalent with regard to antigen structure and polymorphism; furthermore, a number of combinations of specific MHC alleles between HLA-B and HLA-DR/DQ (extended haplotypes) are found in people more commonly than predicted by individual allele frequencies. Over 30 percent of Caucasian haplotypes are extended haplotypes, and over 55 percent of individuals have at least one extended haplotype. Examples of the same extended haplotype, even in unrelated individuals, should either all have or lack any gene within the MHC region. The value of considering extended haplotypes in searching for associations between the MHC and diseases, or immune response, is shown in three examples: congenital adrenal hyperplasia, hepatitis B immunization, and transfusion-associated graft-versus-host disease.
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PMID:The major histocompatibility complex: the value of extended haplotypes in the analysis of associated immune diseases and disorders. 229 6

Major histocompatibility complex-determined antigens were originally identified as a consequence of their ability to induce rejection of tissue grafts between organisms that are not genetically identical. Currently, much is known about their biochemical nature and intended biological functions. Major histocompatibility complex antigens are found on three types of glycoprotein molecules. One type (class I) is associated with beta 2-microglobulin in the cell-surface membranes of all body tissues and includes H-2K and D molecules in mice and HLA-A, B, and C molecules in humans. These antigens are the major cause of rejection of transplanted organs. The other two types of glycoproteins (class II) are noncovalently linked to each other, are found in the cell-surface membranes of a limited number of cell types, and include H-2-Ia molecules in mice and HLA-DR molecules in humans. They are noted for their ability to elicit graft-versus-host disease. Both class I and class II molecules are, however, important for the immune recognition of pathogens, although the types of responses they modulate are different. Class I molecules are important in the recognition of cell-surface antigens, whereas class II molecules control responsiveness to soluble antigens. Major histcompatibility complex-encoded molecules are also involved in certain autoimmune diseases. As our understanding of major histocompatibility complex-controlled immune responsiveness broadens and hybridoma and gene-cloning technology advances, specific enhancement of desired immune responses and suppression of deleterious ones will most likely become possible.
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PMID:Immune-response gene-associated antigens (Ia/DR). Structure and function in immunologically related diseases. 640 18

Major histocompatibility complex (MHC) antigens, termed HLA in man, provide the major barrier to transplantation. Clinical manifestations of the host-versus-graft reaction are generally referred to as rejection and those of the graft-versus-host (GVH) reaction as graft-versus-host disease (GVHD). GVHD can occur after transplantation of marrow or solid organs or transfusion of blood products. GVHD involves antigen-presenting cells, which are recognized by T lymphocytes via the T-cell receptor. CD4 and CD8 serve as accessory molecules. This interaction results in T-cell activation, expression of interleukin-2 receptors (IL-2R) and the production of IL-2 followed, generally, by clonal proliferation and differentiation associated with lymphokine secretion and dysregulation that may involve interferon-gamma; tumor necrosis factor-alpha; IL-2, -3, -4, -5, -6, and -9; granulocyte macrophage colony-stimulating factor (GM-CSF); and other factors. Effector cells such as cytotoxic T cells, natural killer (NK) cells, and macrophages become activated, mostly by bone marrow-derived lymphohemopoietic cells, and contribute to cell and tissue death. Many of the cytokines also alter vascular endothelium; conceivably these changes also affect homing of cells and allogeneic interactions. Another factor is the administration of in vivo GVHD prophylaxis, which may modify both undesirable (GVHD-inducing) and desirable (tolerance-inducing) mechanisms. Exogenous hematopoietic growth factors and cytokines recently introduced into clinical trials may interfere with endogenous feedback loops in a positive or negative fashion. Adverse reactions have been observed with IL-2 and with interferon. Potentially beneficial effects have been reported with the use of soluble IL-1R or IL-1R-antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Graft-versus-host disease: host and donor views. 830 4

Major histocompatibility complex (MHC) molecules carrying selected peptides will bind specifically to their cognate T-cell receptor on individual clones of reactive T cells. Fluorescently labeled, tetrameric MHC-peptide complexes have been widely used to detect and quantitate antigen-specific T-cell populations via flow cytometry. We hypothesized that such MHC-peptide tetramers could also be used to selectively deplete unique reactive T-cell populations, while leaving the remaining T-cell repertoire and immune response intact. In this report, we successfully demonstrate that a tetramer-based depletion of T cells can be achieved in a murine model of allogeneic bone marrow transplantation. Depletion of a specific alloreactive population of donor splenocytes (< 0.5% of CD8+ T cells) prior to transplantation significantly decreased morbidity and mortality from graft-versus-host disease. There was no early regrowth of the antigen-specific T cells in the recipient and in vivo T-cell proliferation was greatly reduced as well. Survival was increased more than 3-fold over controls, yet the inherent antitumor activity of the transplant was retained. This method also provides the proof-of-concept for similar strategies to selectively remove other unwanted T-cell clones, which could result in novel therapies for certain autoimmune disorders, T-cell malignancies, and solid organ graft rejection.
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PMID:Remodeling specific immunity by use of MHC tetramers: demonstration in a graft-versus-host disease model. 1626 13

Development of naturally occurring CD4+CD25+ T regulatory cells (Treg) in the thymus requires the transcription factor Foxp3. Major histocompatibility complex (MHC) class II, self-ligands expressed by epithelial cells, and thymic stromal lymphopoietin also appear to play important roles. In addition, several molecular regulators of T-cell receptor (TCR) signaling (both positive and negative) have been implicated in the control of Treg development. Foxp3 is a transcriptional repressor of IL-2 and other cytokines and appears to maintain the anergic and suppressor function of these cells. Multiple cell types (T cells, B cells, dendritic cells [DC], and natural killer [NK] cells) are targeted by Treg using diverse suppressor mechanisms, whereas factors that regulate Treg proliferation and function, including Toll-like receptor (TLR) ligands, have also been identified. Because Treg play an important role in the control of autoimmunity, therapeutic strategies are being pursued to enhance their numbers and function in specific autoimmune diseases. In transplantation, where Treg also offer potential for therapy of rejection and graft-versus-host disease (GVHD), indirect allorecognition may be the dominant pathway for immune regulation by these cells. In tumor immunology, Treg have emerged as major suppressors of T-cell-mediated antitumor responses and represent a significant obstacle to effective anticancer vaccines. Strategies aimed at depletion/functional inhibition of these cells by molecular targeting must maintain a critical balance between tumor immunity and self-tolerance.
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PMID:Naturally occurring regulatory T cells: recent insights in health and disease. 1743 97

Patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) are threatened by potentially lethal viral manifestations like cytomegalovirus (CMV) reactivation. Because the success of today's virostatic treatment is limited by side effects and resistance development, adoptive transfer of virus-specific memory T cells derived from the stem cell donor has been proposed as an alternative therapeutic strategy. In this context, dose minimization of adoptively transferred T cells might be warranted for the avoidance of graft-versus-host disease (GVHD), in particular in prophylactic settings after T-cell-depleting allo-HSCT protocols. To establish a lower limit for successful adoptive T-cell therapy, we conducted low-dose CD8(+) T-cell transfers in the well-established murine Listeria monocytogenes (L.m.) infection model. Major histocompatibility complex-Streptamer-enriched antigen-specific CD62L(hi) but not CD62L(lo) CD8(+) memory T cells proliferated, differentiated, and protected against L.m. infections after prophylactic application. Even progenies derived from a single CD62L(hi) L.m.-specific CD8(+) T cell could be protective against bacterial challenge. In analogy, low-dose transfers of Streptamer-enriched human CMV-specific CD8(+) T cells into allo-HSCT recipients led to strong pathogen-specific T-cell expansion in a compassionate-use setting. In summary, low-dose adoptive T-cell transfer (ACT) could be a promising strategy, particularly for prophylactic treatment of infectious complications after allo-HSCT.
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PMID:Lowest numbers of primary CD8(+) T cells can reconstitute protective immunity upon adoptive immunotherapy. 2506 Nov 70

Delayed immunological rejection after human lung transplantation causes chronic lung allograft dysfunction, which is associated with high mortality. Delayed rejection may be attributable to indirect alloantigen presentation by host antigen-presenting cells; however, its pathophysiology is not fully understood. The mitogen-activated protein kinase pathway is activated in T cells upon stimulation, and we previously showed that the MEK inhibitor, trametinib, suppresses graft-versus-host disease after murine bone marrow transplantation. We investigated whether trametinib suppresses graft rejection after two types of rat lung transplantation and analyzed its immunological mode of action. Major histocompatibility complex-mismatched transplantation from brown Norway rats into Lewis rats and minor histocompatibility antigen-mismatched transplantation from Fischer 344 rats into Lewis rats were performed. Cyclosporine (CsA) and/or trametinib were administered alone or consecutively. Acute and delayed rejection, lymphocyte infiltration, and pulmonary function were evaluated. Administration of trametinib after CsA suppressed delayed rejection, reduced inflammatory cell infiltration and fibrosis within the graft, and preserved pulmonary functions at Day 28. Trametinib suppressed functional differentiation of T and B cells in the periphery but preserved thymic T cell differentiation. Donor B cells within the graft disappeared by Day 14, indicating that delayed graft rejection at Day 28 was mainly due to indirect presentation by host antigen-presenting cells. Finally, trametinib administration without CsA preconditioning suppressed rejection after minor histocompatibility antigen-mismatched transplantation. Trametinib attenuates delayed rejection upon major histocompatibility complex-mismatched transplantation by suppressing indirect presentation and is a promising candidate to treat chronic lung allograft dysfunction in humans.
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PMID:Trametinib Attenuates Delayed Rejection and Preserves Thymic Function in Rat Lung Transplantation. 3095

Major histocompatibility complex (MHC) class II deficiency is a rare and fatal primary combined immunodeficiency. It affects both marrow-derived cells and thymic epithelium, leading to impaired antigen presentation by antigen presenting cells and delayed and incomplete maturation of CD4+ lymphocyte populations. Affected children are susceptible to multiple infections by viruses, Pneumocystis jirovecii, bacteria and fungi. Immunological assessment usually shows severe CD4+ T-lymphocytopenia, hypogammaglobulinemia, and lack of antigen-specific antibody responses. The diagnosis is confirmed by absence of constitutive and inducible expression of MHC class II molecules on affected cell types which is the immunologic hallmark of the disease. Hematopoietic cell transplantation (HCT) is the only established curative therapy for MHC class II deficiency but it is difficult as affected children have significant comorbidities at the time of HCT. Optimization organ function, implementing a reduced toxicity conditioning regimen, improved T-cell depletion techniques using serotherapy and graft manipulation, vigilant infection surveillance, pre-emptive and aggressive therapy for infection and newer treatments for graft-versus-host disease have improved the transplant survival for children with MHC class II deficiency. Despite persistent low CD4+ T-lymphopenia reported in post-HCT patients, transplanted patients show normalization of antigen-specific T-lymphocyte stimulation and antibody production in response to immunization antigens. There is a need for a multi-center collaborative study to look at transplant survival of HCT and long-term disease outcome in children with MHC class II deficiency in the modern era of HCT.
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PMID:Hematopoietic Cell Transplantation for MHC Class II Deficiency. 3192 28