Why do heart transplant recipients need lifelong immune suppression?

Heart transplant recipients require lifelong immune suppression because the human immune system is designed to protect the body by identifying and attacking foreign substances. Unfortunately, the immune system cannot distinguish between harmful pathogens and a lifesaving transplanted organ; it perceives the donor heart as "nonself" and initiates a coordinated attack to destroy it.12

This rejection process is primarily driven by T lymphocytes, which recognize foreign antigens on the donor tissue and trigger cell-mediated destruction. To prevent this, recipients must take immunosuppressant drugs—such as calcineurin inhibitors—that inhibit the function of these T cells. Because the risk of the immune system identifying and rejecting the foreign heart persists, patients must maintain this medical regimen for life to ensure the graft's survival. While these drugs are essential for preventing rejection, they also require careful monitoring, as they increase the patient's susceptibility to infections.2345