Hylkäämisreaktio

Hylkäämisreaktio, often referred to as rejection in a medical context, is the process by which a recipient's immune system attacks a transplanted organ or tissue. This occurs because the immune system recognizes the transplanted material as foreign due to differences in cell surface markers, primarily the human leukocyte antigen (HLA) system. Even with extensive matching, some degree of immune incompatibility is common.

There are several types of rejection. Hyperacute rejection happens within minutes to hours after transplantation and is caused by pre-existing antibodies in the recipient's bloodstream that attack the organ's blood vessels. Acute rejection typically occurs within the first few weeks to months, involving T-cells and antibodies that target the transplanted organ. Chronic rejection is a slow, gradual process that can occur months or years after transplantation, leading to gradual organ damage and loss of function.

To prevent or manage rejection, immunosuppressive drugs are administered to the recipient. These medications dampen the immune system's activity, making it less likely to attack the transplanted organ. However, these drugs can also increase the risk of infections and other side effects. Regular monitoring of organ function and immune markers is crucial for early detection and management of rejection episodes. While significant advancements have been made, rejection remains a primary challenge in organ transplantation.