Graft-versus-host disease is a common complication of allogeneic bone marrow transplantation. After bone marrow transplantation, T cells present in the graft, either as contaminants or intentionally introduced into the host, attack the tissues of the transplant recipient. Graft-versus-host disease can occur even when HLA-identical sibling are the donors. HLA-identical siblings or HLA-identical unrelated donors (called a minor mismatch as opposed to differences in the HLA antigens, which constitute a major mismatch) often still have genetically different proteins that can be presented on the MHC. Complication, in medicine, is a unfavorable evolution of a disease, a health condition or a medical treatment. ... Bone marrow transplantation is a medical procedure that involves stem cell transplantation. ... Bone marrow is the tissue comprising the center of large bones. ... T cells are a subset of lymphocytes that play a large role in the immune response. ... In horticulture, a graft is where the tissues of one plant are affixed to the tissues of another; the process is called grafting. ... Biological tissue is a group of cells that perform a similar function. ... An organ transplant is the transplantation of an organ (or part of one) from one body to another, for the purpose of replacing the recipients damaged or failing organ with a working one from the donor. ... The human leukocyte antigen system (HLA) is the group of genes in the human major histocompatibility complex (MHC) that encodes the cell-surface antigen-presenting proteins. ... An antigen is any molecule that is recognized by antibodies. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The major histocompatibility complex (MHC) is a large genomic region or gene family found in most vertebrates containing many genes with important immune system roles. ...

While donor T-cells are undesirable as effector cells of graft-versus-host-disease, they are valuable for engraftment by preventing the recipient's residual immune system from rejecting the bone marrow graft (host-versus-graft). Additionally, as bone marrow transplantation is frequently used to cure malignant disorders (most prominently the leukemias), donor T-cells have proven to have a valuable graft-versus-tumor effect. A great deal of current research on allogeneic bone marrow transplantation involves attempts to separate the undesirable graft-vs-host-disease aspects of T-cell physiology from the desirable graft-versus-tumor effect. T cells are a subset of lymphocytes that play a large role in the immune response. ... The immune system is the organ system that protects an organism from outside biological influences. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Leukemia (leukaemia in Commonwealth English) is a group of blood diseases characterized by malignancies (cancer) of the blood-forming tissues. ... See the article about cancer for the main article about malignant tumors. ...

Types

Clinically, graft-versus-host-disease is divided into acute and chronic forms. The acute or fulminant form of the is disease observed within the first 100 days post-transplant, and the chronic form of graft-versus-host-disease is defined as that which occurs after 100 days. This distinction is not arbitrary: acute and chronic graft-versus-host-disease appear to involve different immune cell subsets, different cytokine profiles, and different types of target organ damage. Acute may refer to: An acute accent is a diacritic character. ... The word chronic has uses in many fields. ... White Blood Cells is also the name of a White Stripes album. ... Cytokines are small protein molecules that are the core of communication between immune system cells, and even between these cells and cells belonging to other tissue types. ...

Classically, graft-versus-host-disease is characterized by selective damage to the liver, skin and mucosa, and the gastrointestinal tract. Newer research indicates that other graft-versus-host-disease target organs include the immune system (the hematopoietic system) itself, and the lungs in the form of idiopathic pneumonitis. Chronic graft-versus-host-disease damages the above organs, but also causes changes to the connective tissue (e.g. of the skin). The liver is an organ in vertebrates, including humans. ... Model of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system; which is composed of a layer of tissues that protect underlying muscles and organs. ... The mucous membranes (or mucosa) are linings of ectodermic origin, covered in epithelium, that line various body cavities and internal organs. ... The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ... The immune system is the organ system that protects an organism from outside biological influences. ... Haematopoiesis is the formation of blood cellular components. ... The heart with relation to the lungs (from an older edition of Grays Anatomy) This x-ray of the human chest shows the lungs as dark regions The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Pneumonia (the ancient Greek word for lungs) is defined as an inflammation, usually caused by infection, involving the alveoli of the lungs. ... Connective tissue is any type of biological tissue with an extensive extracellular matrix and often serves to support, bind together, and protect organs. ... Model of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system; which is composed of a layer of tissues that protect underlying muscles and organs. ...

Prevention

Graft-versus-host-disease can largely be avoided by performing a T-cell depleted bone marrow transplant. These types of transplants result in reduced target organ damage and generally less graft-versus-host-disease, but at a cost of diminished graft-versus-tumor effect, a greater risk of engraftment failure, and general immunodeficiency, resulting in a patient more susceptible to viral, bacterial, and fungal infection. In a single-center study at Harvard Medical School's Dana-Farber Cancer Institute, it has been found at the 1.5 year post-transplant timepoint, that T-cell depleted transplants overall performed equally to conventional bone-marrow transplantation as measured by survival and quality of life. Larger multi-center studies are now underway to verify this finding. In medicine, immune deficiency (or immunodeficiency) is a state where the immune system is incapable of defending the organism from infectious disease. ... Three types of viruses: a bacterial virus, otherwise called a bacteriophage (left center); an animal virus (top right); and a retrovirus (bottom right). ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Divisions Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota Yellow fungus For the fictional character, see Fungus the Bogeyman. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Harvard Medical School Harvard Medical School(HMS) is one of the graduate schools of Harvard University. ... Quality of Life (to be released in 2005) is a narrative feature film, telling the fictional story of two graffiti writers in the Mission District of San Francisco. ... In medicine, a clinical trial (synonyms: clinical studies, research protocols, medical research) is a research study. ...

Bibliography

• Graft-vs.-Host-Disease by Ferrara et al. (2nd ed.) published by Marcel Dekker is somewhat out of date, but still a nice bound volume.
• Example journals that publish current research on graft-versus-host-disease include The Biology of Blood and Marrow Transplantation, Journal of Clinical Investigation, Journal of Experimental Medicine, Blood, Journal of Immunology, Nature Immunology, Nature Medicine, Immunity, and Transplantation.

Related topics

• Transplantation
  • Transplant rejection, also known as "host-verses-graft disease"
• Immunology
  • Immunosuppression
• Cancer

An organ transplant is the transplantation of an organ (or part of one) from one body to another, for the purpose of replacing the recipients damaged or failing organ with a working one from the donor. ... Transplant rejection is a process by which the immune system of the recipient of a transplant attacks the transplanted organ or tissue. ... Immunology is a broad branch of biomedical science that covers study of all aspects of the immune system in all organisms. ... Immunosuppression is the medical suppression of the immune system. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ...

External links

• National Marrow Donor Program