What is transplant immunology?

From the Guidelines

Transplant immunology is a complex field that involves the study of immune responses to transplanted organs and tissues, with the primary goal of preventing rejection while maintaining the recipient's ability to fight infections. The liver is considered a privileged organ in terms of immunological interactions, with spontaneous resolution of severe acute rejection episodes having been described in patients after liver transplantation (LT) 1. Key aspects of transplant immunology include:

• HLA matching: Matching human leukocyte antigens (HLA) between donor and recipient to reduce the risk of rejection
• Immunosuppression: Using medications to suppress the recipient's immune system, with tacrolimus (Tac) being the drug of choice in almost 90% of liver transplanted patients, resulting in a significant increase in its use since 1998 to date 1
• Rejection monitoring: Regular blood tests and biopsies to detect early signs of rejection
• Infection prevention: Prophylactic antibiotics, antivirals, and antifungals to prevent opportunistic infections
• Tolerance induction: Developing strategies to induce immune tolerance to the transplanted organ, potentially reducing the need for long-term immunosuppression

The use of immunosuppressive protocols has evolved over time, with a focus on reducing immunosuppression-related side effects, particularly renal toxicity 1. New immunosuppressive agents, such as sirolimus (SRL) and everolimus (EVR), have been developed, but their use is still limited due to concerns about their safety and efficacy 1. The choice of immunosuppressive regimen depends on various factors, including the type of transplant, the recipient's immune status, and the risk of rejection and infection. The most recent and highest quality study recommends the use of Tac as the primary immunosuppressor after LT, due to its ability to reduce mortality, graft loss, and rejection 1.

From the Research

Definition of Transplant Immunology

Transplant immunology refers to the study of the immune system's response to transplanted organs or tissues, and the strategies used to prevent rejection and ensure graft survival.

Key Concepts

• Transplant immunology involves the use of immunosuppressive medications to modulate the immune system's response to the transplanted organ or tissue 2, 3, 4, 5, 6.
• The goal of immunosuppressive therapy is to prevent rejection and graft-versus-host disease, while minimizing the risk of infection and other complications 2, 3, 4, 5, 6.
• Different classes of immunosuppressive medications are used, including polyclonal and monoclonal antibodies, calcineurin inhibitors, antiproliferative agents, mammalian target of rapamycin inhibitors, and corticosteroids 2, 3, 5.

Immunosuppressive Therapy

• Induction, maintenance, and rescue therapy are administered throughout different periods during and after transplantation to prevent or treat rejection or graft-versus-host disease 2.
• The choice of immunosuppressive medications and dosing strategies depends on the type of transplant, the patient's immune status, and other factors 3, 5, 6.
• Monitoring of immunosuppressive medication levels and adjustment of dosing strategies are crucial to prevent toxicity and ensure efficacy 2, 3, 4, 5, 6.

Challenges and Future Directions

• The optimal immunosuppressive therapy post-transplant is not established, and individualized drug use is important to minimize side effects and prevent rejection 3.
• New experimental and clinical studies are needed to discover less toxic but more potent new agents and to develop novel therapeutic approaches based on induction of tolerance and cellular therapy 3, 4, 5, 6.