Organ Transplantation and Allorecognition Flashcards
What can be transplanted?
Cells, tissues, whole organs
Define graft-vs-host disease
T cells from transplanted marrow may attack recipient tissues
Define autograft
Transfer from self to self
Define syngeneic graft
Transfer from genetically identical donor to recipient (twins)
Define allograft
Transfer between genetically distinct individuals, likely rejected
Define xenografts
Donors of different species
What are key factors to avoid organ rejection?
- Matching ABO blood type
2. Matching or similar HLA alleles
What is a major target of graft rejection?
the HLA molecules on MHC molecules since they are the predominant surface molecules on all cells and they are very polymorphic
What are some characteristics of HLA molecules?
- They are the predominant surface molecules on all cells.
2. Highly polymorphic
What type of transplant are most organ transplants?
Allograft
What is the problem with allograft transplants?
They do not have good HLA matches so patients will be on immunosuppressive therapy for life
How does organ rejection occur?
Donor APCs can migrate to recipient’s secondary lymphoid tissues and activate T cells to activate an immune response
Define direct allorecognition
Direct interaction of donor APCs with recipient T cells, which can lead to acute organ rejection within days
Define indirect allorecognition
Donor MHC molecules are processed in recipient APCs, which can contribute to chronic graft rejection by activating antibodies specific for donor MHC antigens
What in the mechanism for direct and indirect rejection?
Rejection is caused by CTL attack, Th1 cell activation of the macrophage-mediated inflammation, ADCC and antibody-mediated activation of complement
