10.2 Organ Grafts

Host's lymphocytes directly recognize and attack donor antigens present on graft cells.

Host's immune system generates antibodies against donor antigens, which then attack graft cells.

A rapid and severe rejection that occurs within minutes to hours after transplantation. It's triggered by pre-existing antibodies in the host's blood that target donor blood vessels.

A rejection that happens within days to weeks after transplantation. It's caused by T cells and antibodies that attack the graft parenchyma and blood vessels.

A slow and progressive rejection that occurs months to years after transplantation. It's caused by the gradual narrowing of blood vessels in the graft, leading to tissue damage and eventual organ failure.

The immune system of the recipient attacks the donated organ due to the presence of foreign antigens. This causes damage to the organ and can lead to rejection.

Rejection that occurs within 7 days of transplantation. It is caused by T cells that recognize the donor organ as foreign.

The major histocompatibility complex (MHC) molecules are the main target of the immune system in allograft rejection. These molecules are highly diverse between individuals, and the immune system can readily recognize them as foreign.

T cells are a type of white blood cell that play a central role in allograft rejection. They can directly attack and destroy the cells of the donor organ, or they can trigger the production of antibodies that damage the organ.

Antibodies are proteins that can bind to and destroy foreign cells. They are produced by the immune system in response to an antigen. In allograft rejection, antibodies can destroy the cells of the donor organ, leading to rejection.

A tissue graft taken from one part of an animal's body and moved to another part of the same animal. This type of graft does not trigger an immune response because it is recognized as 'self'.

A tissue graft transplanted between two genetically identical individuals. This type of graft does not cause an immune response because the individuals have the same MHC markers.

A tissue graft transplanted between genetically different members of the same species. The most frequent type of graft. It triggers a strong immune response due to differences in MHC antigens and blood group antigens, leading to rejection.

A tissue transplant between animals of different species. This type of graft causes the strongest immune reaction and is most likely to be rejected.

The immune response to a foreign organ graft. The immune system recognizes the graft as 'non-self' and tries to destroy it.

A condition that occurs when donor immune cells attack the recipient's tissues. This can happen after bone marrow transplants.

Differences in MHC (Major Histocompatibility Complex) genes between the donor and recipient are the primary cause of graft rejection. The immune system uses MHC markers to identify 'self' and 'non-self'.

Graft rejection can be prevented by using immunosuppressive drugs to suppress the immune system's activity. This allows the body to tolerate the foreign tissue.

A condition where the inner lining of a blood vessel is replaced by smooth muscle cells and connective tissue. This can obstruct blood flow.

A process where the body's immune system attacks and destroys a transplanted organ or tissue (allograft).

Drugs that suppress the immune system's activity to prevent allograft rejection.

Drugs that block the production of specific signaling molecules that activate T cells, thus preventing their excessive activation.

Drugs that kill rapidly dividing T cells, which are often involved in allograft rejection.

Antibodies that target and destroy T cells or block their activation.

Drugs that block the co-stimulatory signals essential for T cell activation.

A condition where grafted immune cells attack the host's tissues, often occurring in immunocompromised patients.

The role of the immune system in identifying and destroying cells that are not recognized as 'self' (non-self). This is the main reason why foreign organ grafts are rejected.

The rejection of a graft occurs when the recipient's immune system identifies the graft as 'foreign' and mounts an attack to destroy it. This can happen due to differences in MHC molecules, which are responsible for recognizing 'self' cells.

Differences in MHC (Major Histocompatibility Complex) genes between the donor and recipient are the primary cause of graft rejection. The immune system uses MHC markers to identify 'self' and 'non-self'. Think of it as a barcode system for the body.

A rapid and severe rejection reaction occurring within minutes to hours after transplantation. It is triggered by pre-existing antibodies in the host's blood that target donor blood vessels, causing immediate damage.

This type of rejection happens within days to weeks after transplantation and involves immune cells attacking the graft's parenchyma and blood vessels. It is caused by T cells and antibodies, leading to inflammation and damage to the transplanted organ.

This slow and gradual rejection process can occur months to years after transplantation. It involves the gradual narrowing of blood vessels in the graft, leading to tissue damage and eventual organ failure. This is caused by the growth of smooth muscle cells inside the blood vessel walls.

This pathway involves host lymphocytes directly recognizing and attacking donor antigens present on graft cells. It's a direct attack on the foreign tissue.

This pathway involves the host's immune system generating antibodies against donor antigens. These antibodies then attack graft cells, indirectly leading to their destruction.

The immune system's primary targets in allograft rejection are the MHC molecules (Major Histocompatibility Complex) and blood group antigens.

A repeated graft from the same donor will be recognized by the recipient's immune system as foreign and will be rapidly rejected, involving both antibodies and complement.

The recipient may show signs like a rapidly rising blood creatinine, enlarged and painful kidney, depression, anorexia, vomiting, proteinuria, and hematuria. Ultrasonography may reveal an enlarged, hypoechoic kidney.

The recipient may show signs like gradually rising creatinine and urea levels, proteinuria, macroscopic hematuria, and a small, hyperechoic kidney.

A tissue graft transplanted between genetically different members of the same species. The most frequent type of graft. It triggers a strong immune response due to differences in MHC antigens and blood group antigens, leading to rejection.

The MHC molecules trigger T cell responses, and blood group antigens trigger antibody formation. The target of the immune system in this process are antigens.

A repeated graft from the same donor will be recognized by the recipient's immune system as foreign and will be rapidly rejected, involving both antibodies and complement.

The process of allograft rejection involves a sequence of steps starting with immune system recognition of foreign antigens present on the graft, followed by T cell activation and antibody production, leading to inflammation, damage, and rejection of the transplanted tissue.

The grafted tissue gradually becomes infiltrated with cytotoxic T cells, which damage the endothelial cells lining small blood vessels. This damage attracts more T cells, leading to cellular destruction, stoppage of blood flow, hemorrhage, and death of the grafted organ.

The recipient might present with a rapidly rising blood creatinine, an enlarged and painful kidney, depression, anorexia, vomiting, proteinuria, and hematuria. Ultrasonography may reveal an enlarged, hypoechoic kidney.

The recipient might present with gradually rising creatinine and urea levels, proteinuria, macroscopic hematuria, and a small, hyperechoic kidney.