Transplantation Flashcards
What is the indirect pathway of allorecognition?
Uses MHCII
- Donors MHC is processed in APC of the recipient.
- The donor MHC are presented as MHCII molecules
Which pathway is seen with chronic rejection?
Indirect pathway
What is hyper acute rejection?
- Minutes to hours
2. Via preformed anti donor anditbodies and complement factors
What is accelerated rejection?
- Occurs in days
2. Reactivation of sensitized T cells
What is an acute rejection?
- Occurs in days to weeks
2. Consists of primary activation f T cells
What is a chronic rejection?
- Occurs over months to years
- Caused by immunological and non-immunologic factors.
- Not manageable with immunosuppressants
Which type of cells cause cellular acute rejection?
Th1
What type of cells cause humoral acute rejection?
Th2
Explain what a hyper acute graft rejection is.
Pre-existing antibodies of the recipient (specific to the donor) already exist. Causing complement activation, endothelial damage, inflammation, thrombosis within minutes to hours.
What are different possibilities that can lead to hyperacute graft rejection?
- ABO blood group incomparable
- Recipient is sensitized to donor MHC (recipient T cells convert memory of previous exposure)
- Classical complement activation
- Endothelial death via complement
What cells have a primary role in acute graft rejection?
The donor DCs of passenger leukocytes
When is a primary immune response generated in an acute graft rejection and where does this occur?
- Primary immune response occurs when donor DC drain from the transplanted organ to the LN, and cause cell activation
What happens in acute graft rejection after the primary immune response is initiated?
- T cells migrate to donor organ and cause tissue damage.
2. Caused by CD4/CD8+ T cells
What are the 2 ways that tissue damage can occur in acute graft rejection after the primary immune response occurred?
- CTL generation
2. Induce delayed-type hypersensitivity reaction
What is a common cause of chronic rejection?
- Occlusion so far blood vessels causes organ ischemia
What are common non-immunologic factors contributing to chronic graft rejection?
- Ischemia-reperfusion damage
- Disease recurrence
- Nephrologist drug effect