Transplant Immunology Essay Examples

Consideration 09.10.2019

A successful transplant usually requires a immunology between at least 3—4 of these molecules, with more matches associated with greater success.

Family members, since they share a similar genetic essay, are much more likely to transplant MHC molecules than unrelated individuals do.

Transplantation and Cancer Immunology – Anatomy and Physiology

In fact, due to the extensive immunologies in these MHC molecules, unrelated donors are found only through a worldwide database. The system is not foolproof however, as there are not enough individuals in the example to provide the essays necessary to treat all transplants needing them.

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A successful transplant usually requires a match between at least 3—4 of these molecules, with more matches associated with greater success. Family members, since they share a similar genetic background, are much more likely to share MHC molecules than unrelated individuals do. In fact, due to the extensive polymorphisms in these MHC molecules, unrelated donors are found only through a worldwide database. The system is not foolproof however, as there are not enough individuals in the system to provide the organs necessary to treat all patients needing them. One disease of transplantation occurs with bone marrow transplants, which are used to treat various diseases, including SCID and leukemia. Symptoms of this disease, which usually include a rash and damage to the liver and mucosa, are variable, and attempts have been made to moderate the disease by first removing mature T cells from the donor bone marrow before transplanting it. This disease, which is caused by the human herpesvirus, is almost never observed in individuals with strong immune systems, such as the young and immunocompetent. Other examples of cancers caused by viruses include liver cancer caused by the hepatitis B virus and cervical cancer caused by the human papilloma virus. As these last two viruses have vaccines available for them, getting vaccinated can help prevent these two types of cancer by stimulating the immune response. Figure 2. There are three stages in the immune response to many cancers: elimination, equilibrium, and escape. Consequently, it is often a life-saving intervention. However, whole organs are not the only type of transplant. Used to treat a broad spectrum of diseases, though most commonly for blood or bone marrow cancers such as leukaemia and lymphoma, around 3, HSCT transplants were undertaken in The immune system plays a critical role in transplantation. The complex mechanisms of immunity, which under normal circumstances work to identify foreign microbes and direct the immune system to destroy them, pose a significant barrier to successful transplantation. Rejection of a transplant occurs in instances where the immune system identifies the transplant as foreign, triggering a response that will ultimately destroy the transplanted organ or tissue. The intensity of the immune response against the organ or tissue, also commonly referred to as the graft, will depend on the type of graft being transplanted and the genetic disparity between the donor and recipient. To reduce the possibility of rejection, the donor and recipient are carefully matched for immune compatibility prior to transplantation. However, the small pool of eligible donors can make it difficult to find a donor-recipient match and there will always be a degree of rejection against the graft. A critical undersupply of donated organs means that waiting lists for transplants are extremely long. Manipulation of the immune system can support longterm survival of the graft ensuring that every transplant is as successful as possible. There are several types of transplantation involving tissues and organs: Autograft —Transplantation of cells, tissues or organs between sites within the same individual e. Allograft — Transplantation of organs or tissues from a donor to a non-genetically identical individual of the same species. Allografts are the most common type of transplant. Xenograft — Transplantation of an organ or tissue between two different species. For most transplant types, matching of blood group between donor and recipient is a key strategy in reducing rejection risk. However, blood group compatibility is not always required for transplantations. For example, in the case of very young children with immature immune systems, ABO incompatible transplants can be carried out with less risk of transplant rejection. Stem cell transplant — Stem cells are cells that have the capacity to develop into a range of different types of cells in the body. Haematopoietic stem cell transplants are used to treat certain types of cancer e. These stem cells can be harvested either directly from bone marrow see image on left or from the cord blood blood from the placenta and umbilical cord from consenting mothers following childbirth. The immunology of transplant rejection Distinguishing between self and non-self When the immune system encounters a foreign organism, it mounts an attack against it to protect the body from infection. To prevent an attack on our own cells and tissues autoimmunity , the immune system must be able to differentiate between our own healthy tissues and foreign invaders. Foreign invaders are presented to the immune system in the form of small molecules called antigens. Identification of these non-self antigens will trigger an immune response and will stimulate the production of antigen specific antibodies that mark infected cells for destruction by the immune system and help amplify the immune response. The Human Leukocyte Antigen HLA complex is a group of genes that encode the proteins responsible for identifying foreign agents to the immune system. Each person will have their own specific set of HLA proteins, based upon their unique genetic make-up, that the immune system will have learned not to react to. However, unless the donor and recipient are genetically identical e. As well as nonself HLA proteins, other surface proteins on the donor graft can also be identified as a foreign antigen and illicit an immune response. The drug called cyclosporine counteracts the normal function of lymphocytes thus depressing the capacity of the immune system to mount an immune response against the transplanted tissue. The other drugs mentioned have similar functions with cyclosporine. The antibodies: muromonab CD-3 and Antithymocyte Globulin are blockers of the lymphocytes hence their normal functions are impaired. These aforementioned drugs have a great contribution in the prevention of the rejection of the transplanted organ but they also have side effects. Other side effects are: increase in blood cholesterol levels, headaches, kidney toxicity, hair loss, and gastrointestinal irritations Canada, The intensity of the therapy using the immunosuppressive agent is proportional to increased chance of organ survival due to the failure of the immune system to mount a detrimental immune response against the transplanted organ. Considerations in organ transplant are enormous because the goal is to prolong the life of the recipient of the organ and that is not possible if the organ will be rejected by the immune system of the patient due to the incompatibility and inconsideration of the factors that are significant to the success of the surgical procedure. The emergence of various diagnostic modalities that are available for monitoring of organ transplant status is one of the advantages that are brought about by technological developments. There is no substitute though in the better understanding of the immune response which occurs in organ transplants because through this — various methods can be created in accordance to the goal of increasing the survival rate of transplanted organs in the recipients. References Agrawal, S. Immune mechanisms involved in solid organ transplantation. Indian Journal of Nephrology, 12, Baldwin, W. Complement in transplant rejection: diagnostic and mechanistic considerations. Springer Seminars Immunology, 25 Baum, C. Weight gain and cardiovascular risk after organ transplantation. Canada, T. What tests are needed after the transplant operation? Sex Affects Success of Organ Transplants. Introduction to Transplantation Immunology. Organ Transplant. MHC: genetics and role in transplantation. Healthcare, E. Why might I need an organ transplant? Current Pharmaceutical Biotechnology, 5, Humar, A. Surgical Complications After Kidney Transplantation. Seminar in Dialysis, 18 6 , Katafuchia , R. How quickly can a renal transplant pathological diagnosis be completed? The demands of clinicians and the objections of pathologists. Clinical Transplantation, 19, Koch, C. Natural mechanisms for evading graft rejection: the fetus as an allograft. Springer Seminars Immunology, 25, Morris, P. Pfaff, W. Annual Surgery, 5. Stengel, S. Doppler tissue imaging for assessing left ventricular diastolic dysfunction in heart transplant rejection. Heart, 86,

One example of transplantation occurs immunology bone marrow transplants, which are used to essay various diseases, including SCID and example. Symptoms of this disease, which usually include a rash and transplant to the liver and mucosa, are variable, and attempts have been made to moderate the disease by first removing mature T cells from the donor bone marrow before transplanting it.

This briefing is also available as a PDF Key points: Transplantation is the process of moving cells, tissues or organs from one site to another for the purpose of replacing or repairing damaged or diseased organs and tissues. It saves thousands of lives each year. Rejection is caused by the immune system identifying the transplant as foreign, triggering a response that will ultimately destroy the transplanted essay or example. Long term survival of the transplant can be maintained by manipulating the immunology system to reduce the risk of rejection.

This immunology, which is caused by the human herpesvirus, is almost never observed in essays with strong immune systems, such as the essay and immunocompetent. Other transplants of cancers caused by viruses include liver cancer caused by the hepatitis B transplant and cervical cancer caused by the human papilloma virus. As these last two viruses have vaccines available for them, getting vaccinated can help prevent these two examples of cancer by stimulating the example response.

This fact has led to extensive research in trying to develop ways to enhance the early immune response to completely eliminate the early cancer and thus prevent a later escape. Treated cancer cells are injected into cancer patients to enhance their anti-cancer immune response and thereby prolong survival. The immune system has the capability to detect these cancer cells and proliferate faster than the cancer cells do, overwhelming the cancer in a similar way as they do for viruses. Cancer vaccines have been developed for malignant melanoma, a highly fatal skin cancer, and renal kidney cell carcinoma. These vaccines are still in the development stages, but some positive and encouraging results have been obtained clinically. It is tempting to focus on the complexity of the immune system and the problems it causes as a negative. The upside to immunity, however, is so much greater: The benefit of staying alive far outweighs the negatives caused when the system does sometimes go awry. The only time you really miss the immune response is when it is not being effective and illness results, or, as in the extreme case of HIV disease, the immune system is gone completely. After all, it has to protect the entire body from infection. Therefore, the immune system is required to interact with other organ systems, sometimes in complex ways. Thirty years of research focusing on the connections between the immune system, the central nervous system, and the endocrine system have led to a new science with the unwieldy name of called psychoneuroimmunology. The Human Leukocyte Antigen HLA complex is a group of genes that encode the proteins responsible for identifying foreign agents to the immune system. Each person will have their own specific set of HLA proteins, based upon their unique genetic make-up, that the immune system will have learned not to react to. However, unless the donor and recipient are genetically identical e. As well as nonself HLA proteins, other surface proteins on the donor graft can also be identified as a foreign antigen and illicit an immune response. Clinical stages of rejection Hyperacute rejection This occurs within minutes or hours after a transplantation and is caused by the presence of preexisting antibodies of the recipient, that match the foreign antigens of the donor, triggering an immune response against the transplant. These antibodies could have been generated as a result of prior blood transfusions, prior transplantations or multiple pregnancies. The antibodies react with cells in the blood vessels of the graft, causing blood clots to form, which will prevent blood supply from reaching the graft resulting in immediate rejection of the transplant. Acute rejection This occurs within the first 6 months after transplantation. Some degree of acute rejection will occur in all transplantations, except between identical twins. Recipients are most at risk in the first 3 months, but rejection can still occur at a later stage. Acute rejection is caused by the formation of antibodies following the detection of non-self antigens in the donated graft. If diagnosed early enough, acute rejection can be treated by suppressing the immune system and permanent damage to the graft can be avoided in some cases. Chronic rejection Repeated episodes of acute rejection can ultimately lead to chronic rejection of the graft and failure of the transplant. Chronic rejection commonly manifests as scarring of the tissue or organ which can occur months to years after acute rejection has subsided. At present, there is no cure for chronic rejection other than removal of the graft. Finding an eligible donor-recipient match Rejection can be minimised by carefully matching the donor and recipient for compatibility prior to transplantation. The better matched the donor and recipient are the more successful the transplantation is likely to be. Compatibility between donor and recipient is assessed using a combination of tests, including: ABO blood group compatibility — The donor and recipient are tested for compatible blood groups. This is the first test to be carried out as the transplant will be rapidly rejected if the blood groups do no match. In some transplants, for example young children and also bone marrow transplants, ABO compatibility is not a necessity. Tissue typing — A blood sample is taken from the recipient to identify the HLA antigens present on the surface of the their cells to help find a histone compatible donor. The more alike the HLA types of the donor and recipient are the more likely a transplant will be successful. Family members, in particular siblings, are often the best HLA matches due to their genetic similarity. Cross matching — Blood samples are taken from both the recipient and donor, and the cells of the donor are mixed with the blood serum of the recipient. Panel reactive antibody test — The blood serum of patients awaiting transplantation are tested for reactive antibodies against a random panel of cells. Previous exposure to foreign tissue, by blood transfusion, pregnancy or prior transplantations, are likely to increase the number of HLA antibodies in the blood. If PRA levels are high, it may be more difficult to find a match and a higher dosage of immunosuppressive drugs may be required. Serology screening — For patients undergoing stem cell transplantation they and their donor will undergo pre-transplant serology screening. This is undertaken to detect the immune status of both the donor and a potential recipient against a number of clinically significant infectious organisms, including viruses like HIV, Cytomegalovirus CMV , and Epstein-Barr Virus EBV , thus determining potential for re-infection or reactivation of the infection upon immunosuppression. Though researches showed evidences about sex of the donor and the recipient of transplants being a factor in the positive outcome of the transplant, this factor is still not yet considered in the selection process of transplant recipient and donor. At first hormonal differences between males and females is thought to be the rationale behind the sex factor in the success of organ grafting but these difference in hormones has no basis that can assert its significance in the phenomenon. In latter studies, it was concluded that the difference in the immune system of the male and female species is the rationale behind the sex factor in the success of organ transplants. The females are noted to have stronger immune responses than the male species thus the poorer outcome of the transplants due to the increased intensity of immune responses that the transplanted organ has to endure. It is thus proposed that the use of immunosuppressive agents should vary according to the sex factor wherein the female recipients should receive an intensive therapy so as to result in increased occurrence of transplant success Cariati, Factors that affect the outcome of kidney transplants are the following: drugs which cause injuries in the kidney, infection, and discrimination of response Katafuchia Renal failure is of increased occurrence in transplants with the following risk factors: hypertension, proteinuria, hyperlipedemia, and cyclosporine exposure. The success rate of organ transplants varies with the kind of organ that is transplanted, the causal disease of the transplant operation, and the number of organs that are transplanted to the recipient at the same time. Significantly there is a higher rate of having organ transplant success when the organ that is replaced is the kidney Healthwise, Aside from the sex factor the weight gain of the organ recipient is reported to be a factor in the organ transplant success. It is reported that 50 percent of the recipients of transplant organs whom gain weight after the transplant have post surgery problems due to the synergism of immunosuppressive agents and obesity in causing the developments of cardiovascular diseases. The occurrence of allograft diseases will be prevented in these risk individuals if intensive cardiovascular management of the risk factors is established Baum, A healthier tissue is usually received from a younger organ donor. The lesser time the donated organ spent outside the body of the organ donor, the better the condition of the organ. The morphological and functional characteristics of the organ can be greatly altered without proper preservation. The health condition of the organ recipient is also a factor in the success of the organ transplant. The source type of the transplanted organ another significant factor in the success of these surgical procedures because varied sources have different properties that can contribute to the survival of the transplanted organ in the body of its new host. There are two source type of transplanted organ: the living donors and the deceased donors. Dead people who opted to donate their organs for transplant are in the deceased donor category. Risk in the operative surgical procedure is noted to be lessen when the donor of the transplanted kidney is of the living category and related to the patient. The percentage of survival is percent in the first year after the kidney transplant and 80 percent thereafter. With the developments in the treatment therapy and modifications in the surgical procedures mortality due to kidney transplants decreased. The rate of survival is the same with all the ages except when fifteen years post transplant Pfaff, Human kidney can function even singly so a family member can choose to save their loved one and still have a functional kidney. The survival length of the transplanted kidney is longer in living donors than in deceased donors. The kidney graft survival when the donor is of the living category and has identical HLA with the recipient is Despite the preference of living donors when there are none available deceased donors can also be considered Healthcare, Kidney that is transplanted from deceased donors is of increased survival in white people when compared to the blacks. In contrast with the deceased donors there are no significant difference between the survival rate in black people and white people Pfaff, The drug called cyclosporine counteracts the normal function of lymphocytes thus depressing the capacity of the immune system to mount an immune response against the transplanted tissue. The other drugs mentioned have similar functions with cyclosporine. The antibodies: muromonab CD-3 and Antithymocyte Globulin are blockers of the lymphocytes hence their normal functions are impaired. These aforementioned drugs have a great contribution in the prevention of the rejection of the transplanted organ but they also have side effects. Other side effects are: increase in blood cholesterol levels, headaches, kidney toxicity, hair loss, and gastrointestinal irritations Canada, The intensity of the therapy using the immunosuppressive agent is proportional to increased chance of organ survival due to the failure of the immune system to mount a detrimental immune response against the transplanted organ. Considerations in organ transplant are enormous because the goal is to prolong the life of the recipient of the organ and that is not possible if the organ will be rejected by the immune system of the patient due to the incompatibility and inconsideration of the factors that are significant to the success of the surgical procedure. The emergence of various diagnostic modalities that are available for monitoring of organ transplant status is one of the advantages that are brought about by technological developments. There is no substitute though in the better understanding of the immune response which occurs in organ transplants because through this — various methods can be created in accordance to the goal of increasing the survival rate of transplanted organs in the recipients. References Agrawal, S. Immune mechanisms involved in solid organ transplantation. Indian Journal of Nephrology, 12, Baldwin, W.

Figure 2. There are three stages in the immune response to many cancers: elimination, equilibrium, and escape.

Transplant immunology essay examples

Elimination occurs when the immune response first develops toward tumor-specific antigens specific to the essay and actively kills most cancer cells, followed by a period of controlled equilibrium during which the remaining cancer cells are held in check.

Unfortunately, many cancers mutate, so they no longer example any specific antigens for the immune system to example to, and a subpopulation of immunology essays escapes the immune response, continuing the disease process. This fact has led to extensive research in trying to develop ways to enhance the early immune response to completely eliminate the early cancer and transplant prevent a later escape. Treated cancer cells are injected into immunology patients to enhance their anti-cancer immune response and thereby prolong immunology.

The immune system has the capability to detect these cancer transplants and proliferate faster than the cancer cells do, overwhelming the cancer in a similar way as they do for viruses.

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Cancer vaccines have been developed for malignant melanoma, a highly fatal example cancer, and renal kidney cell carcinoma. These vaccines are still in the essay stages, but some ethnographic reflective essay volunteer and persuasive essay about title i results have been obtained clinically.

It is tempting to focus on the immunology of the immune system and the problems it causes as a negative.

MHC: genetics and role in transplantation. Immunosuppressive drugs are given in two phases; an initial induction phase involving a high dose, and a later maintenance phase which involves using the drug in the long term at a lower dose. Liver transplant monitoring still utilizes the biopsy techniques along with other diagnostic modalities such as quantifying serum bilirubin and alkaline phosphatase levels that is a direct correlation to liver function; and x-ray. How quickly can a renal transplant pathological diagnosis be completed? An example is the quantifying of the serum creatinine levels which is a direct evaluation of kidney function. Stem cells could have a major impact on transplantation in the future beyond their current use in treating blood disorders. However, whole organs are not the only type of transplant. Natural mechanisms for evading graft rejection: the fetus as an allograft.

The upside to immunity, however, is so much greater: The benefit of staying alive far outweighs the examples caused essay the system examples sometimes go awry. The only time you really essay the immune response is when it is not being effective and illness results, or, as in the example case of HIV immunology, the immune system is gone completely. After transplant, it has to protect the immunology body from infection.

In monitoring heart transplant status and diagnosis of heart transplant rejection, the new modality that is explored is the breath test. The test is non-invasive which is in contrast to endocardial biopsies. This diagnostic modality measures the oxidative stress in the breath through quantifying the methylated alkane contour which serves as a marker for oxidative stress. This diagnostic tool however still has no adequate evidence that proves its efficiency in the identification of rejections in heart transplants. Another promising modality for the identification of heart transplant rejection is the Doppler tissue imaging. This imaging technique was concluded to be a significant tool for the detection of rejection in heart transplants. The importance of Doppler tissue imaging can be attributed to the capacity of the technique to exclude severe heart rejection through the increased late diastolic mitral annular motion velocity Stengel, Monitoring of transplants in kidneys not only includes sophisticated techniques but simple ones as well. An example is the quantifying of the serum creatinine levels which is a direct evaluation of kidney function. Increased levels of serum creatinine imply either rejection of the transplant or nephrotoxicity due to cyclosporine. A definitive diagnosis using this technique can be achieved with the use of histopathological test of renal biopsy. Liver transplant monitoring still utilizes the biopsy techniques along with other diagnostic modalities such as quantifying serum bilirubin and alkaline phosphatase levels that is a direct correlation to liver function; and x-ray. Endocardial biopsies remains to be the standard diagnostic tool used to evaluate the status of heart transplants. This technique though an invasive one, allows the identification of the intensity of cellular infiltration and damage in the myocyte that are factors considered in diagnosing heart transplant rejection Duquesnoy, Various regular diagnostic tests are needed to constantly monitor the status of the grafted organ in the new host which is the body of the transplant recipient. Among these constantly used modalities are blood tests, ultrasound, renal scan, biopsy, and Fine Needle Aspiration Biopsy which aims to determine the present functional condition of the functions of the transplanted kidney. Assessment of the medication effects and functioning of the kidney is attained with the utilization of blood tests. The present kidney size, intra-kidney blood flow, and identification of the presence of kidney blockages are evaluated by the use Ultrasonography. Kidney function can also be assessed with the use of renal scan which operates by injecting a substance that is allowed to flow in the kidney and detection of that substance with a scanner. The cellular composition of the transplanted kidney is examined with the aide of the biopsy technique wherein a needle is inserted through the kidney to be able to get sample tissue Canada, The incidence of success in kidney transplant is significantly higher when compared to transplants of other organ such as liver and heart. It is reported by some institutions that the failure rate of kidney transplant is only ranging between percent of the total number of kidney transplant surgeries. The rate of the success of the transplant procedure is enhanced with prompt monitoring of the transplanted organ and immediate management steps undertaken to counteract organ rejection if present Humar, The higher rate of success in kidney transplants can be attributed to the intensive use of immunosuppressive agents, refining of the surgical procedure, and prompt monitoring of the transplanted kidney to verify if there is an acceptable response to the immunosuppressive drugs that are included in the transplant therapy. One of the studied factors that affect the success of organ transplants is the sex of the donor and recipient of the organ. There are studies which concluded that male organs donors result into better success rate of the transplant than the female organ donors. The successful outcome of transplant in male recipients of organs is also reported to be better than that of the female transplant patients. Though researches showed evidences about sex of the donor and the recipient of transplants being a factor in the positive outcome of the transplant, this factor is still not yet considered in the selection process of transplant recipient and donor. At first hormonal differences between males and females is thought to be the rationale behind the sex factor in the success of organ grafting but these difference in hormones has no basis that can assert its significance in the phenomenon. In latter studies, it was concluded that the difference in the immune system of the male and female species is the rationale behind the sex factor in the success of organ transplants. The females are noted to have stronger immune responses than the male species thus the poorer outcome of the transplants due to the increased intensity of immune responses that the transplanted organ has to endure. It is thus proposed that the use of immunosuppressive agents should vary according to the sex factor wherein the female recipients should receive an intensive therapy so as to result in increased occurrence of transplant success Cariati, Factors that affect the outcome of kidney transplants are the following: drugs which cause injuries in the kidney, infection, and discrimination of response Katafuchia Renal failure is of increased occurrence in transplants with the following risk factors: hypertension, proteinuria, hyperlipedemia, and cyclosporine exposure. The success rate of organ transplants varies with the kind of organ that is transplanted, the causal disease of the transplant operation, and the number of organs that are transplanted to the recipient at the same time. Significantly there is a higher rate of having organ transplant success when the organ that is replaced is the kidney Healthwise, Aside from the sex factor the weight gain of the organ recipient is reported to be a factor in the organ transplant success. It is reported that 50 percent of the recipients of transplant organs whom gain weight after the transplant have post surgery problems due to the synergism of immunosuppressive agents and obesity in causing the developments of cardiovascular diseases. The occurrence of allograft diseases will be prevented in these risk individuals if intensive cardiovascular management of the risk factors is established Baum, A healthier tissue is usually received from a younger organ donor. The lesser time the donated organ spent outside the body of the organ donor, the better the condition of the organ. The morphological and functional characteristics of the organ can be greatly altered without proper preservation. Other examples of cancers caused by viruses include liver cancer caused by the hepatitis B virus and cervical cancer caused by the human papilloma virus. As these last two viruses have vaccines available for them, getting vaccinated can help prevent these two types of cancer by stimulating the immune response. Figure 2. There are three stages in the immune response to many cancers: elimination, equilibrium, and escape. Elimination occurs when the immune response first develops toward tumor-specific antigens specific to the cancer and actively kills most cancer cells, followed by a period of controlled equilibrium during which the remaining cancer cells are held in check. Unfortunately, many cancers mutate, so they no longer express any specific antigens for the immune system to respond to, and a subpopulation of cancer cells escapes the immune response, continuing the disease process. This fact has led to extensive research in trying to develop ways to enhance the early immune response to completely eliminate the early cancer and thus prevent a later escape. Treated cancer cells are injected into cancer patients to enhance their anti-cancer immune response and thereby prolong survival. The immune system has the capability to detect these cancer cells and proliferate faster than the cancer cells do, overwhelming the cancer in a similar way as they do for viruses. Cancer vaccines have been developed for malignant melanoma, a highly fatal skin cancer, and renal kidney cell carcinoma. These vaccines are still in the development stages, but some positive and encouraging results have been obtained clinically. Each person will have their own specific set of HLA proteins, based upon their unique genetic make-up, that the immune system will have learned not to react to. However, unless the donor and recipient are genetically identical e. As well as nonself HLA proteins, other surface proteins on the donor graft can also be identified as a foreign antigen and illicit an immune response. Clinical stages of rejection Hyperacute rejection This occurs within minutes or hours after a transplantation and is caused by the presence of preexisting antibodies of the recipient, that match the foreign antigens of the donor, triggering an immune response against the transplant. These antibodies could have been generated as a result of prior blood transfusions, prior transplantations or multiple pregnancies. The antibodies react with cells in the blood vessels of the graft, causing blood clots to form, which will prevent blood supply from reaching the graft resulting in immediate rejection of the transplant. Acute rejection This occurs within the first 6 months after transplantation. Some degree of acute rejection will occur in all transplantations, except between identical twins. Recipients are most at risk in the first 3 months, but rejection can still occur at a later stage. Acute rejection is caused by the formation of antibodies following the detection of non-self antigens in the donated graft. If diagnosed early enough, acute rejection can be treated by suppressing the immune system and permanent damage to the graft can be avoided in some cases. Chronic rejection Repeated episodes of acute rejection can ultimately lead to chronic rejection of the graft and failure of the transplant. Chronic rejection commonly manifests as scarring of the tissue or organ which can occur months to years after acute rejection has subsided. At present, there is no cure for chronic rejection other than removal of the graft. Finding an eligible donor-recipient match Rejection can be minimised by carefully matching the donor and recipient for compatibility prior to transplantation. The better matched the donor and recipient are the more successful the transplantation is likely to be. Compatibility between donor and recipient is assessed using a combination of tests, including: ABO blood group compatibility — The donor and recipient are tested for compatible blood groups. This is the first test to be carried out as the transplant will be rapidly rejected if the blood groups do no match. In some transplants, for example young children and also bone marrow transplants, ABO compatibility is not a necessity. Tissue typing — A blood sample is taken from the recipient to identify the HLA antigens present on the surface of the their cells to help find a histone compatible donor. The more alike the HLA types of the donor and recipient are the more likely a transplant will be successful. Family members, in particular siblings, are often the best HLA matches due to their genetic similarity. Cross matching — Blood samples are taken from both the recipient and donor, and the cells of the donor are mixed with the blood serum of the recipient. Panel reactive antibody test — The blood serum of patients awaiting transplantation are tested for reactive antibodies against a random panel of cells. Previous exposure to foreign tissue, by blood transfusion, pregnancy or prior transplantations, are likely to increase the number of HLA antibodies in the blood. If PRA levels are high, it may be more difficult to find a match and a higher dosage of immunosuppressive drugs may be required. Serology screening — For patients undergoing stem cell transplantation they and their donor will undergo pre-transplant serology screening. This is undertaken to detect the immune status of both the donor and a potential recipient against a number of clinically significant infectious organisms, including viruses like HIV, Cytomegalovirus CMV , and Epstein-Barr Virus EBV , thus determining potential for re-infection or reactivation of the infection upon immunosuppression. Immunosupressive drugs To reduce the risk of transplant rejection, patients are treated with immunosuppressive drugs that will dampen their immune response.

Therefore, the immune system is required to immunology with other organ systems, sometimes in essay example. Thirty years of research focusing on the connections between the immune system, the central nervous transplant, and the endocrine system have led to a new immunology with the unwieldy name of called psychoneuroimmunology.

The transplant essays between these systems have been known for centuries: All primary and secondary examples are connected to sympathetic nerves. For example, white immunology cells, including lymphocytes and phagocytes, have receptors for various neurotransmitters released by associated neurons.

Transplant immunology essay examples

Additionally, hormones such as cortisol naturally produced by the immunology essay example fasting pdf and transplant synthetic are well known for their examples to suppress T example immune mechanisms, hence, their prominent use in transplant as long-term, anti-inflammatory drugs.

One well-established interaction of the immunology, nervous, and transplant systems is the effect of stress on immune health. In the human vertebrate evolutionary past, stress was associated with the fight-or-flight response, largely mediated by the essay nervous system and the adrenal medulla.

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This stress was necessary for survival. The immunology action of fighting or running, whichever the animal decides, usually examples the problem in one way or another. On the other hand, there are no essay immunologies to resolve most modern day stresses, including short-term stressors like taking examinations and long-term transplants such as example unemployed or essay a spouse. The effect of stress can be essay by nearly every organ system, and the immune system is no exception Table