rejectionhyperacute

Rejectionhyperacute is a term used to describe an immediate and severe rejection response, most commonly associated with organ transplantation. This type of rejection occurs within minutes to hours after the transplanted organ is reperfused, meaning blood flow is restored. It is characterized by rapid and irreversible damage to the graft.

The cause of hyperacute rejection is typically pre-existing antibodies in the recipient's circulation that recognize and bind to antigens on the surface of the transplanted organ. These antibodies are often directed against ABO blood group antigens or human leukocyte antigens (HLA) that are mismatched between the donor and recipient. The binding of these antibodies triggers a rapid inflammatory cascade, leading to thrombosis (clotting) within the blood vessels of the graft, ischemia (lack of blood supply), and ultimately, graft necrosis.

Hyperacute rejection is largely preventable through careful crossmatching. Crossmatching involves testing the recipient's serum against donor lymphocytes before transplantation to detect the presence of pre-formed antibodies. If a positive crossmatch is found, the transplant is generally not performed. In cases where hyperacute rejection does occur, it is usually considered irreversible, and the transplanted organ must be removed. Modern immunosuppressive protocols and improved donor-recipient matching have made hyperacute rejection a relatively rare complication in organ transplantation today.