Organ transplantation
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- Organs are vital to the functioning of the human body which are self-contained and have a specific vital role that contributes to the functioning of the body.
- Organ transplantation occurs if a persons organs has failed due to an injury or illness. Surgeons remove an organ from either a living or dead organ donor and put it into the recipient so they can have an efficient and functioning organ.
- Doctors try and match the recipient as close as possible to the donor to reduce the risk of rejection. Rejection is where the immune system doesn't deem the organs cells as 'self' and therefore starts to attack the new organ
- Kidney failure, lung disease and heart disease are just a few conditions that might be able to be treated by organ transplantation.
- The immune system recognises self cells by the MHC class marker molecules.
- These molecules are composed of genes that allow t-cells to distinguish between self and non-self cells
- As the genetic makeup of and individual is so unique, each individual will have slightly different MHC marker molecules.
- This is why a tissue type test must be taken before a transplant is made. A tissue type test is a blood test that identifies antigens to see if the donor tissue is compatible with that of the recipient. If the donors tissues are similar organ rejection would be less likely to occur. However in some cases where the donor MHC molecules are too different, organ rejection would occur.
- This occurs when the immune system of the recipient does not identify the new organ as self and therefore rejects the organ by deeming it non-self and attacking it
- If the new organ has different marker molecules organ rejection would occur due to the genetic makeup of the MHC markers being so different to the recipients MHC markers.
- The T-cells would identify the donors MHC class markers as foreign and initiate the humoral response. As the donor organ would be under attack this would lead to cellular death and therefore organ death. However there are certain drugs that can prevent this
IMMUNOSUPPRESANT (ANTI-REJECTING) DRUGS
- The immune system can be modified by altering the function of T-cells to prevent organ rejection
- This is achieved by the recipient with the new organ in place consuming immunosuppresant drugs for the rest of their lives
- As the name suggests these drugs suppress the immune system by inhibiting T-cell activation and therefore stopping mainly the 3rd line of defense. This allows for the organ that would be deemed non-self to function efficiently without being attacked.
- However, as the immunosuppresants inhibit the immune system to function efficiently there would be a higher chance for the individual to be prone to illnesses and diseases due to the last line of defense being inactive.
- There are four types of immunosupressant drugs:
-Asathioprines: Interrupt the synthesis of DNA, RNA and meiosis/mitosis
-Monoclonal antibodies: Reduces the production rate of t-cells
-Corticosteroids: Reduce the inflammation in the area in the case of an organ transplant rejection.
- Thee recipient may need to take a combination of drugs or just one type depending on the success rate of their transplant.
- There may be a reduction in the amount of drugs taken as the rejection rate of the organ decreases however usually recipients will have to take at least one type of these drugs for the rest of their lives.