Transplant rejection is a critical challenge in solid organ transplantation, occurring when the recipient’s immune system recognizes the transplanted organ as foreign and mounts an attack against it. This immune response is driven by the recognition of donor antigens by the host’s T cells, triggering the release of pro-inflammatory cytokines and the activation of both innate and adaptive immune responses. Rejection can manifest in different forms—hyperacute, acute, and chronic—each with varying onset and severity.
Hyperacute rejection happens within minutes due to pre-existing antibodies, while acute rejection typically occurs days to weeks post-transplant, primarily mediated by T cells and cytotoxic immune responses. Chronic rejection, a long-term complication, involves gradual tissue damage and fibrosis, leading to organ failure over time.
Despite advancements in immunosuppressive therapies, rejection remains a significant cause of graft loss and patient morbidity. These drugs, while effective, carry risks of infection and other side effects. Therefore, exploring safer and more targeted immunomodulatory strategies is crucial. Understanding the cellular and molecular mechanisms of rejection can lead to innovative treatments—such as natural compounds like those in green tea—which offer the potential to promote immune tolerance while minimizing adverse effects, ultimately enhancing transplant survival rates.
