Lecture 4 Transplantation Flashcards
Define autologous transplant
Refers to tissue returning to the same individual after a period outside of the body
Define Syngeneic transplant
Isograft
Transplant between identical twins
Define Allogeneic transplant
takes place between genetically nonidentical members of the same species; there is always a risk of rejection.
Define cadaveric transplantation
Uses organ from dead donor
Define Xenogeneic transplant
Takes place between different species and carries the highest risk of rejection
What is the criteria for solid organ transplant
Evidence that damage is irreversible
Alternative treatments are not applicable
Disease must not recur
What precautions are carried out to reduce risk of rejection (4)
Donor and recipient must be ABO compatible
Recipient must have anti-donor HLA antibodies
Donor should be close HLA match
Patient must take immunosuppressive treatment
Define hyper-acute rejection
Rejection within hours of transplantation
Antibody binding triggers a type II hypersensitivity reaction
Define acute rejection
Type IV
Takes place within days or weeks of transplantation
Describe the afferent phase of the immunopathology of graft rejection
Donor MHC molecules on dendritic cells are recognised by recipients CD4+ T cells (allorecognition)
Describe the efferent phase of the immunopathology of graft rejection
CD4+ T cells recruit effector cells responsible for the tissue damage, macrophages, CD8+ T cells, NK and B lymphocytes
Define chronic rejection
Rejection takes place months or years after transplant
Name the 2 main tissue typic techniques
HLA typing HLA cross matching with B cells (express class I and class II HLA)
When is allogenic stem cell transplant carried out?
Haem malignancy
Aplastic anaemia
SCID
What are the sources of stem cells
Bone marrow
Peripheral blood
Cord blood
How is a patient prepared prior to receiving stem cells
High dose chemo and radiotherapy
Destroy recipients stem cells
What is Graft versus Host Disease
Occurs when donor T cells respond to allogenic recipient antigens
How do corticosteroids work as immunosuppressive drugs
Act on APC at low doses
Direct effect on T cells at higher doses
How do T-cell signalling blockades work as immunosuppressives (Cyclosporine and Tacrolimus)
Work by interacting with proteins in the intracellular T-cell signalling cascade
Why does IL-2 blockade immunosuppress
Activated T cells secrete IL-2 which binds to receptors on neighbouring T cells and stimulates division
How doe antiproliferatives immunosuppress
Inhibit DNA production
Name examples of anti-proliferatives
Azathioprine
Mycophenolate
Mofetil
Methotrexate
What are the side effects of cyclosporin
Increased infections Increase risk of getting certain cancers Nephrotoxic Diabetes Hypertension
What are the side effects of Rapamycin
Raised lipid and cholesterol level Hypertension Anaemia Diarrhoea Rash Acne Thrombocytopenia
