A/41 Flashcards
What types of hypersensitivity are involved in graft rejection?
- Type 2 : ab mediated
- Type 4 : cell mediated
Which type of hypersensitivity is for each pathway?
- Type 2 / AB mediated : indirect pathway
- Type 4 / cell mediated : direct pathway
What are the 3 principle pathomechanisms of rejection?
- Donor express MHC I that is recognized by recipient CD8 cells as non-selves
- Donor express MHC II that is recognized by CD4 cells
- Shedded graft cell antigens are presented by recipient RES
How do CD4 cells transform into TH2 cells?
By binding MHCII complex with B7 cofactor
Types of graft rejections (3)
- Hyperacute rejection
- Acute rejection
- Chronic rejection
What is hyperacute rejection a result of?
A result of humoral immunity : patient had been sensitized before to the antigen
What is acute rejection a result of?
cellular and humoral immunity
When does acute rejection occur?
days or weeks after transplantation
What is chronic rejection a result of?
cytokine expression / release of inflammatory cells
What does humoral immunity cause? (3)
- necrotizing vasculitis
- thrombosis
- endothelial fibrosis
Consequences of chronic rejection? (4)
- intimal SMC proliferation
- increased ECM synthesis
- narrowed lumen
- ischemia of organ
How to increase graft survival? (4)
- better matching donor and recipient HLA genes
- global, life-long immunosuppression
- Anti-CD3 treatment
- Blocking cofactors of dendritic cells (CD28, B7…)
Types of bone marrow transplantation (2)
- autologous
- allogenic
What cells are harvested in autologous transplantation?
CD34 cells of patient in remission
