Diverse Roles of Immune Cells in Transplant Rejection and Immune Tolerance

Organ transplant rejection (OTR) is a complex immune reaction involving multiple cells, and it determines graft survival and patient prognosis. At present, most transplant recipients are administered a combination of immunosuppressive and biological agents to protect them from OTR. However, immunosuppressive agents negatively impact the immune system of the patients, causing them to suffer from serious complications, such as chronic infection and malignant tumors. Therefore, a thorough understanding of the mechanisms involved in immune tolerance and immune rejection with regard to organ transplant (OT) is essential for developing better treatment options and improving patient outcomes. This article reviews the role of immune cells in OTR and organ transplant tolerance (OTT), including the novel cell therapies that are currently under clinical trials for transplant recipients.