Sunday, March 31, 2019

Transplant Rejection: Causes, Types and Prevention

communicate Rejection Causes, Types and PreventionThrough this project I chip in researched commutes of harmoniums, cells and winds, transfer rejection, the compassionate Immune System and the fiber of antibodies. Transplatation is the process where flushed cells, interweave or pipe electronic organs ar moved from peerless web site to an early(a). There be several(predicate) events of displaces and some problems that evict march on with organ engraftation. The largest menace to a successful organ transplant is the Human Immune System, because it rejects the transplant.The role of the gentle immunity dodging is to protect the personify from harmful, infecting agents. It smashs the transplant recognizing it as out perspective(prenominal) and a potential treat to the luggage com disassociatement. This is cognise as counterchange Rejection.There atomic number 18 many different types of engraft Rejection, each with thither own diagnosis methods and sympt oms. There atomic number 18 different ways of barroom and treatment, including create from raw stuff typing to determine the most appropriate presenter- recipient check up on and development Immunosuppressant drugs that suppress the resistant remains of the recipient.There ar deuce casts of immunity in a benignant. The bodys first line of defence is the innate(p) freedom and the particularised reply to the invaders is the adaptive Immunity. Many exsanguinous occupation cells form the main components of the resistant form and they identify and destroy assail agents.There are similarly different types of resistive responses including the humoral immune response. Antibodies, Y-shaped proteins, form part of the Humoral response. The structure of all antibodies are actually similar, except for a small unique region at the ends of the twain arms of the Y used for recognising agents. Antibodies can destroy the alien tangible or support destroy them by tagging it for outrage by an new(prenominal)(prenominal) parts of the immune system.Antibodies are very fundamental in transplant rejection, because they form part of the mechanism that rejects the organ or tissue and are one of the most important cells of the Human Immunity System. They help entrust to Transplant Rejection and the destruction of the transplanted organ or tissue.INDEX (Jump to)Introduction surmiseTransplantsTypes of TransplantsProblems With TransplantationTransplant RejectionTypes of Transplant RejectionDiagnosis and SymptomsPrevention and Treatment potency Further StudiesThe Human Immune System and AntibodiesTypes of Immune ResponsesConclusionBibliography Referencing triggerThe role of the Human Immunity System is to protect the body from harmful, infecting agents. This shelter is very important to keep our bodies heavy and functioning at the crush it can, just this protection is also the largest problem in organ and tissue transplants.Transplantation has replaced many people damaged organs with healthy organs and is used to cure many tissue and cell complaints. The Human Immunity System is the largest threat to successful organ and tissue transplants, but why does the Human Immunity reject the transplanted organ or tissue? And is it feasible that transplant rejection can be prevented?The body is constantly under attack from harmful substances that can cause damage and destruction to the human body, but we are protected. The human immunity system is bodys natural defence mechanism. What causes an immune response? And how does the immune system respond to exotic satisfyings?Antibodies are an important part in the human immunity system. They can separate, neutralize and destroy harmful materials, but what exact role does an antibody play in human immunity? Where and why are antibodies produced?Through this project I exit explore transplants, transplant rejection, human immunity and the role of antibodies and finally elicit or contradict my hypothesis.HYPOTHESISAntibodies do non play a role in the rejection of a transplanted organ or tissue.TransplantsTransplatation is the action of healthy cells, tissue or organs that are transplanted ( organ transplanted) from one site to another. A transplanted organ can replace a recipients damaged, malfunctioning or remove organ and embeding of cells and tissue can also cure many diseases.A kidney (most common), heart, lungs, pancreas, liver, skin, cornea, argument, argumentation vessels, bone warmheartedness, stem cells, cord blood, intestine, stomach, testis, thymus, bones, tendons, heart valves and veins, hand, Islets of Langerhans and ovaries can now be transplanted. The transplanted organ or tissue is comm sole(prenominal) known as a graft.While the lack of organs for transplantation clay an obstacle, the biggest challenge for transplantation is the immune system. It destroys a transplanted graft recognizing it as strange and a potential treat to the body. 2791112 13141516171819202122Types of TransplantsAutografts Grafts of tissue from one area of the body to another part e.g. Skin transplants, vein extractions, etc. Autografts are not unknown tissue and on that pointfore there is no immune answer.Allografts Grafts amongst members of the same species. Most organ transplants are allografts. Because of genetic differences amongst the organ and the recipient, the recipients immune system ordain identify the organ as contradictory and attempts to destroy it, causing transplant rejection.Isografts Forms part of allografts and are grafts between genetically identical individualists. Isografts do not trigger an immune response.Xenografts/ Xenotransplantation Grafts between members of different species. E.g. the use of organs from other animals, like chimpanzees, baboon and pigs. In Xenografts there is a large risk of rejection and diseases carried in the tissue. 279192022Problems with TransplantationGraft/transplant rejection The immune syst em, recognizing the transplanted graft as contrasted, allow cause a rejection of the graft.Graft-versus-host disease (GVHD) T-cells, in the graft from the bestower, identify the tissues of the recipient as a unknown antigen and mounts an immune attack against them. This is prevented by removing all T-cells in the graft in the contractning transplantation.In rare boldnesss the donated organ whitethorn be give and transmit an agent to the recipient. E.g. TB, rabies, syphilis, hepatitis B, HIV and many other diseases. To prevent this, potential donors are tested for these infections before the transplantation. 21219Transplant RejectionTransplant rejection is also know as Graft Rejection and organ or tissue rejection.Transplant Rejection occurs when a transplanted organ or tissue is not accepted by the body of the recipient, because the immune system of the recipient attacks and tries to destroy the transplanted organ or tissue. The body identifies the graft as foreign material a nd and so triggers a rejection.This is expected because the Human Immunity Systems purpose is to protect the body by identifying and destroying foreign material that are potentially harmful. These harmful substances boast proteins called antigens on their climbs, when the immune system identifies these antigens as foreign, it will start to attack them.The degree and type of response varies according to the type of transplant and the organ or tissue be transplanted. Certain sites in the body are immune privileged, which means they are protected from attack, because immune cells and antibodies do not reach them. The anterior bedroom of the eye, the testes and the brain are all immune privileged.Using the patients own tissue for autografts or tissue from an identical twin, isografts, when avai research lable prevents transplant rejection as the recipient sees the transplant as self, not as foreign and therefore does not mount an attack. Using a relative (sibling) as a donor is als o recommended, because they may have inherited some of the same histocompatibility antigens and therefore the immune response may not be as strong. 23478111223Types of Transplant RejectionHyperacute RejectionHyperacute Rejection is a rare humoral complement-mediated response in recipients with pre-existing antibodies to the donor. This reaction occurs immediately after(prenominal) the transplantation. No treatment is available for it and the graft essential be removed quickly to prevent a severe superior general inflammatory response or death. cutting RejectionAcute rejection usually begins one week after the transplant, but it can occur months to long time after transplantation. The new organ will be incapable of working at full efficiency. A single episode of acute rejection is not dangerous, if it recognize and treated it rarely leads to organ failure.Acute rejection occurs to some degree in all transplants and is caused by mismatched HLA. The Immune system will recognize t he graft as foreign and will mount an attack against it. Acute rejection is a form of Cell-mediated response.Humeroral RejectionHumeroral Rejection is mediated by antibody and complement Immunity. It can occur immediately or during the first week after the transplantation. The antibodies are preformed antibodies or anti-donor antibodies that have developed after transplant.Chronic RejectionChronic Rejection is the rejection against a graft due to chronic inflammatory and immune response. This rejection occurs over time (sometimes years after the transplant) and may occur from repeated episodes of acute rejection or for other causes not understood.Chronic Rejection is rare and is both antibody cell-mediated immune responses. Chronic rejection is permanent and there is no successful treatment. Eventually the donor organ is lost, wind to re-transplant or death. 37823Diagnosis and SymptomsDiagnosis of transplant rejection relies on clinical data, including signs and symptoms, lab tes ting and a tissue biopsy to confirm that the graft has been rejected. The biopsy is interpreted by a pathologist who notes changes in the tissue that suggest rejection. E.g. presence of T-cells and other cell types that may be helpful in diagnosing the type of rejection and any evidence of structural injury or injury to blood vessels in the transplanted tissue.The symptoms of transplant rejection vary depending on the organ or tissue transplanted, but general symptoms include the organ not functioning properly, general discomfort, uneasiness or ill feeling, pain or swelling in the location of organ (rare) and fever (rare). 123Prevention TreatmentTissue typeTransplant rejection can be reduced through serotyping (tissue typing or crossmatching) before the transplantation to identify the antigens it contains and to determine the most appropriate donor-recipient match. indigene blood typing or HLA (Tissue antigen) typing is performed to ensure that the organ or tissue is as similar a s possible to the tissues of the recipient.The antigens responsible for rejection of tissues are called histocompatibility antigens. These antigens are encoded by genes on chromosome 6, called the Major Histocompatibility Complex (MHC). The MHC is called the Human Leukocyte Antigen (HLA) system in humans. HLA are present on all cells of the body. apiece individual has a unique combination of HLA and matching as many histocompatibility antigens will minimize the size and speed of rejection.MHC molecules present antigens to the T-cells of the immune system. When a foreign material enters a body cell, the MHC molecules inside the body cell get to the antigen and transport it to the body cells surface. The antigen can now be recognized by a T-cell.Immunosuppressant DrugsImmunosuppressant drugs can treat and prevent transplant rejection. The drugs suppress the immune system of the recipient and are usually demand for all transplants to prevent the graft from being rejected. The drugs should be used for the alleviation of the transplant recipients life.Most immunosuppressive drugs have the disadvantage of being non- precise and they allow in suppression of the entire immune responses and therefore placing the recipient at a higher risk of infections. It is needed to develop more specific immunosuppressive drugs that will suppress only the responses that attack the graft, without dangerous side effects.Drugs like azathioprine (Imuran), methotrexate, cyclophosphamide, prednisone, belatacept, corticosteroids, cyclosporine A, tacrolimus, prednisolone, mycophennolate mofetil, antithymocyte globulin (ATG) and rapamycin are routinely used in different combinations for a safe level of immunosuppression.Side effects of immunosuppression drugs include infections, as the immune system is vital to protect us from infectious agents (bacteria, viruses, fungi, etc). commonly the infections can be controlled by the appropriate antibiotic, antiviral drug, etc. The see of Canc er is also increased with the use of immunosuppression drugs. 12567812161923Potential Further StudiesDemi-Lee Brennan, an Australian whose body changed blood type and adopted the immune system of her donor after a liver transplant. Her body no longer rejects the transplanted liver. Her case is unique and scientists are interested in finding out how this occurred. duplicate of this would be a potential solution to transplant rejection.Some grafts come through despite the presence of anti-donor antibodies. This acquired resistance to antibody-mediated damage is known as modification and is poorly understood. 68The Human Immune System and AntibodiesThe immune system recognizes as foreign and attacks anything different from your normal body tissues. Even substances that are only slightly different, for example a transplanted organ or tissue, are considered foreign invaders.The immune system uses histocompatibility antigens to recognize material as self or foreign. Antigens occur on t he surface of every cell and the immune system will attack anything that does not display the antigen of that individual. The immune system cannot enumerate if the foreign material is harmful or not, just that it is different. The transplanted organ or tissue is different and therefore the immune system will accentuate to destroy it.There are twain kinds of immunity in a human, native Immunity and Adaptive Immunity. The bodys first line of defence against invaders is the Innate Immunity. It is provided by barriers like tears, mucus, skin, saliva and the rapid inflammation of tissue. If an invader gets away the Innate Immunity, the immune system will make a customized defence, the Adaptive Immunity. It is a specific response depending on the specific invader and it has a memory, which allows it to respond better to the specific invader if it attacks again. The Adaptive Immunity does not attack normal body components, only substances it recognizes as non-self.White blood cells (l eukocytes) are the main component of the immune system. Macrophages, a type of white blood cells, surround and eat occupy materials. Macrophages can also confiscate to themselves to invading agents and transport them to another part of the immune system to be destroyed. Lymphocytes are specialized white blood cells that identify and destroy invading antigens. Each lymphocyte has a unique antigen receptor on its surface that can bind to a matching antigen on the surface of the foreign invader. They constantly travel throughout the body feel for invaders. All lymphocytes begin as stem cells in bone marrow, but they mature in two different places.Several lymphocytes mature in the bone marrow and they are called B-lymphocytes (B-cells). B-cells form Plasma cells that make antibodies. Each B-cell has a unique receptor on its tissue layer, called B-cell receptor (BCR) that is designed to fit a specific antigen. When the BCR binds to an antigen molecule, the B-cell surrounds it and bre aks it up. The result is the histcompatibilty molecules and past the body B-cell can identify the antigen.Other lymphocytes called T-lymphocytes (T-cells) mature in the thymus. Some T-cells called cytotoic or Killer T-cells directly destroy cells that are displaying a certain antigen on their surface. Other T-cells, Helper T-cells, regulate the immune system by controlling the strength of immune responses. 135678101123Types of Immune ResponsesHumoral Immune ResponseThe Humoral response attack invaders that act alfresco of cells, like bacteria and poisons.When an invader antigen enters the body, Macrophages take the antigen and attach it to MHC molecules. The MHC molecules display the antigen to the T-helper cells and they attach to the presented antigen. This stimulates the T-helper cells to divide and produce interleukins. The Interleukins activate a B-cell that has bound the antigen. The activated B-cells then divide and secrete antibodies.Antibodies, also called immunoglobulin s (lg), are Y-shaped proteins and they are found in blood and other bodily fluids of vertebrates. Antibodies are produced by a kind of white blood cell, called a plasma cell.Surface immunoglobulin are attached to the membrane of the effector B-cells, while antibodies are the secreted into the bloodstream and body cavities. The membrane-bound form of an antibodies is forms part of the BCR on B-cells.The general structure of all antibodies are very similar, except for a small region at the ends of the two arms of the Y used for natural covering antigens. This allows many different antigen binding sites to exist between the antibodies, allowing the immune system to recognize a tolerant diversity of antigens.The base of the Y determines how the antibody will destroy an antigen or foreign material. Antibodies into are classified into 5 classes/isotypes lgM, lgG, lgA, lgD and lgE. They perform different roles and form part of the immune response against foreign objects.The secreted anti bodies bind can the antigen and destroy it. Antibodies may also stop the harmful effects of an antigen by attaching to it and neutralizing it. Antibodies also help destroy antigens by tagging it for attack by other parts of the immune system.Cell-mediated Immune ResponseThe Cell-mediated Response attacks invaders, like viruses, that reproduce inside cells. It also destroys cells that cause the growth of improper structures, like cancers. later on an invader antigen enters the human body, Macrophages attach the antigen to MHC molecules. The MHC molecules present the antigen to the T-helper cells and they bind the antigen, which motivates the T-helper cells to divide and secrete interleukins. The Interleukins activate killer whale T-cells. Killer T-cells directly destroy the cell/s that are infected with or that are producing a certain antigen. 3781011CONCLUSIONMy Hypothesis that antibodies do not play a role in the rejection of a transplanted organ or tissue is incorrect. Antibodies are very important in transplant rejection, because they form part of the mechanism that rejects the organ or tissue and they are one of the main components of the Human Immunity System.When the healthy organ or tissue is transplanted into the body of the recipient, it does not have the same tissue antigens of the recipients body. Each human has unique tissue antigens, therefore a perfect match is seldom found.Antibodies form part of humoral rejection response to the transplanted organ or tissue. They are the main element in recognizing a foreign agent, because they have unique antigen binding sites. Antibodies especially play a role in Hyperacute, Humeroral and Chronic Transplant Rejection, as they are all humoral-mediated rejections.Anti-Donor antibodies are secreted by plasma cells after the T-helper cells have collected the transplants antigen and identified it as foreign and non-self. Pre-existing antibodies circulate through the bodily fluids of the human body looking for for eign material to recognize. Some antibodies also form part of the membrane receptor of the B-cells used to identify and recognize antigens of the transplanted organ or tissue.After the antibodies have bond to the foreign antigen of the transplanted organ or tissue, therefore recognizing it, it will decide how to destroy the organ or tissue or if it will tag it for attack from other parts of the immune system. Leading to Transplant Rejection and the destruction of the transplanted organ or tissue.BIBLIOGRAPHY REFERENCINGWebsiteshttp// obligate/000815.htm, Transplant Rejection, Medline Plus, 23 February 2010, David A. 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