Mechanisms of rejection: current perspectives

Area of Science:

• Immunology
• Transplantation Science
• Molecular Biology

Background:

• Transplant rejection is a primary obstacle in organ and cell transplantation.
• The immune response involves a complex interplay between the innate and adaptive immune systems.
• Tissue injury during retrieval and ischemia-reperfusion initiates and amplifies the adaptive immune response.

Discussion:

• T cell activation requires antigen recognition and costimulation, with naive T cells having stricter requirements than memory T cells.
• Memory T cells, common in transplant recipients due to heterologous immunity, influence rejection dynamics.
• B cell antibody production often requires T cell help, contributing to rejection through various antibody targets.

Key Insights:

• Antibodies targeting donor human leukocyte antigen (HLA) molecules, minor histocompatibility antigens, or self-antigens can drive early and late rejection.
• Antibody-mediated rejection, involving alloantibody binding and complement activation, is a significant cause of graft loss.
• Rejection is typically multifactorial, integrating multiple immune mechanisms rather than being solely T cell or antibody-mediated.

Outlook:

• Identifying molecular pathways of tissue injury and signal transduction is crucial.
• This understanding facilitates the development of targeted immunosuppressive therapies.
• Future strategies aim to mitigate the integrated immune response to improve transplant success rates.