Flashcards in Transplantation Deck (30)
What are the 3 stages of transplant rejection?
3) Effector function
What is recognised following a transplantation?
HLA - A, B, DR = these are the most important
Minor HLA - other polymathic self peptides
ABO Blood Antigens
What are the two types of recognition that occur in transplantation?
What is Direct Transplant Recognition?
Donor APC presenting antigen and/or MHC to recipient T-cells. Acute rejection mainly involves direct presentation
What is Indirect Transplant Recognition?
Recipient APC presenting donor antigen to recipient T-cells - i.e. the immune system working normally, as it would for an infection. Chronic rejection mainly involves indirect presentation
Hyperacute Transplant Rejection - Time frame?
Hyperacute Transplant Rejection - Mechanism?
Preformed Ab which activates Complement
Hyperacute Transplant Rejection - Pathology?
Thrombosis and Necrosis
Hyperacute Transplant Rejection - Treatment?
Prevention - Crossmatching
Acute Cellular Transplant Rejection - Time frame?
Acute Cellular Transplant Rejection - Mechanism?
CD4 activating a Type IV reaction
Acute Cellular Transplant Rejection - Pathology?
Acute Cellular Transplant Rejection - Treatment?
Acute Antibody Mediated Transplant Rejection - Time frame?
Weeks - Months
Acute Antibody Mediated Transplant Rejection - Mechanism?
B-cell activation - antibody attacks vessels
Acute Antibody Mediated Transplant Rejection - Pathology?
Acute Antibody Mediated Transplant Rejection - Treatment?
Ab removal and B-cell Immunosuppression
Chronic Transplant Rejection - Time frame?
Months - Years
Chronic Transplant Rejection - Mechanism?
Immune and non-immune mechanism
Chronic Transplant Rejection - Pathology?
Chronic Transplant Rejection - Treatment?
Minimise Organ Damage
Graft v Host Disease - Time frame?
Days - weeks
Graft v Host Disease - Mechanism?
Donor cells attack Host
Graft v Host Disease - Pathology?
Skin (rash), Gut (D+V, bloody stool) and liver (jaundice) involvement
Graft v Host Disease - Treatment?
Prevention/ Immunosuppression - corticosteroids
T cells recognise antigen with MHCs, B cells can recognise just antigen
APCs present antigen to T cells (dendritic cells, Macrophages, B cells)
Tissue Matching for Transplant
Important to reduce Antigen differences and therefore recognition and rejection
1) determine donor and recipient blood group and HLA type - PCR. Maximise similarity
2) Check recipients pre-formed Ab against ABO and HLA - via CDC (complement Dependent Cytotoxicity), FACS (flow cytometry) and Luminex (like solid phase FACS- can pick up abs to individual HLAs)
3) Cross Match- via CDC and FACS. test if serum from recipient is able to bind/kill donor lymphocytes - positive crossmatch is contraindicated for transplantation
4) after transplant check again for new antibodies vs the graft
Pre-transplant induction agents?
Suppress T cell responses e.g. anti CD52 Alemtuzumab or anti-CD25 Basiliximab
What can you use to treat repeat episodes of acute rejection?
Cellular - Steroids, IVIG
Ab-mediated - IVIG, plasma exchange, anti-c5