graftrejection

Graft rejection is a process that occurs when a recipient's immune system recognizes a transplanted organ or tissue as foreign and attacks it. This immune response is a natural defense mechanism aimed at eliminating invaders. The immune system identifies the cells of the transplanted graft by their surface markers, primarily the human leukocyte antigens (HLAs), which are unique to each individual, except in the case of identical twins.

There are three main types of graft rejection: hyperacute, acute, and chronic. Hyperacute rejection happens very rapidly, within minutes to hours of the transplant, due to pre-existing antibodies in the recipient's blood that target the donor organ's blood vessels. Acute rejection typically occurs within days to weeks, involving T-cells and antibodies attacking the graft. Chronic rejection is a slower process that can take months or years, leading to gradual damage and loss of function of the transplanted organ.

To prevent or manage graft rejection, immunosuppressive drugs are administered to the recipient. These medications suppress the immune system, making it less likely to attack the transplanted organ. However, these drugs also increase the risk of infections and other side effects. Careful monitoring of the recipient and the transplanted organ is crucial to detect and manage any signs of rejection. Tissue typing, which involves matching HLAs between donor and recipient, is performed before transplantation to minimize the risk of rejection.