Why transplants are rejected

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.

The more HLA antibodies present, the higher he panel reactive antibody PRA level denoted to the patient, and the greater the chance of graft rejection. 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.

To reduce the risk of transplant rejection, patients are treated with immunosuppressive drugs that will dampen their immune response. 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. The combination of drugs, and dosage given, will vary depending on the type of transplant and the chosen treatment regime.

If a patient experiences an episode of acute rejection the drug combination is subject to change and the dosage is also likely to increase. Side effects can also cause alternative drugs to be used. Steroids, in the past, have been the most commonly used immunosuppressant drug. However, their use is being reduced due to the adverse side effects associated with them. All current immunosuppressive drugs come with limitations. One of the major limitations of these drugs is immunodeficiency.

As these immunosuppressive drugs are non-specific, they will reduce overall immune system function leaving patients susceptible to opportunistic infection. Additionally, many of these drugs are associated with adverse side effects, such as high blood pressure, impaired renal function, diabetes mellitus, and increased risk of cancer — to name just a few. Patients are required to take a large number of immunosuppressants each day for the rest of their lives, which can have a major impact on their health and lifestyle.

Good hand washing, vaccinations for you and your family, food safety practices and specific guidelines pertaining to your transplant can help you stay healthy. Organ rejection symptoms vary by the type of organ transplant you've had. If you experience fever, pain or other signs of illness, contact the transplant center right away.

The first step: We will give you medicines to counter the rejection. Organ rejection often requires a biopsy and a hospital stay, along with tests and monitoring. Certain types of rejection may require more intense or lengthy treatments. Home Services Transplant Transplant Rejection. In This Section. Transplant Rejection. Summary of transplant rejection mechanisms.

Figure 2. Types of allorecognition. Bitesize category Organs and Tissues. Related Articles Transplant rejection: T-helper cell paradigm. Stem cell transplantation. Lymph Node. Innate immunity in the large intestine. This is known as organ rejection. Every transplant patient experiences an immune reaction to the donor organ, but whether and how organ rejection occurs varies from person to person.

There are different types of rejection, including acute and chronic rejection. Acute rejection is shorter in duration and often occurs in the first few months after transplant. Chronic rejection is ongoing and may cause the donor organ to lose function over time. Because immunosuppressant drugs affect the whole immune system, they can leave a transplant recipient vulnerable to other infections. Though some new immunosuppressant drugs have been developed that interact with T or B cells in different ways, immunosuppressant therapies have not changed much over the last several decades.

If it does, that T cell activates by replicating itself over and over. These replica T cells all target that specific foreign molecule; they also trigger other parts of the immune system to respond. Once we have isolated those T cells responsible for attacking a transplanted organ, we can study them to understand what makes them unique and how they damage the organ.

Our focus is on lung transplantation. Research on lung transplantation has lagged behind other areas because this surgery was relatively uncommon until recent years.