Flashcards in Lecture 20 Thrush Deck (17):
What is graft rejection due to?
Specificity and memory
First set rejection and how long?
Takes 1-2 weeks for immunological response and rejecion because it usually takes 1-2 weeks for immune system to get going when new antigen is recognized
Second se rejection
takes a hand full of days
quicker- it remembers from first transplant
What is the role of CD8 t cells is graft rejection?
CD8 cells don't play much of a role by themselves, by adding antibodies against CD8 cells, you will still experience rejection in 15 days.
What is the role of CD4 cells in graft rejection
Inserting antibodies against CD4 cells led to a rejection 30 days later, better that t cells but not permanent because new CD4 cells will be regenerated
What is the role of the combination of both CD4 and CD8 cells?
with both, the rejection doesnt take place until after 60 days
What are the 2 major steps in graft rejection?
Sensitization phase and effector phase
What does the sensitization stage include?
What does alloreactive mean?
differences between individuals (donor to recepienct) are recognized and cause the activation of CD4 and CD8 cells
What can help to increase the survival of graft during the alloreactive?
exposing blood cells to recipient from donor before the graft may increase the survival of the graft. body may be tricked into thinking the cells are auto cells after its developed tolerance
What is the role of host DCs
they can move into the tissue and gobble up donor antigen causing activation t cells to give rise to the cytoines or antibodies to come in and destroy the tissue
Which cells are included in the effector cells?
DTH- cause inflammation (Th1 cells) (neutrophils, macro dcs come and make situation worse)
CTL- mediate cytotoxicity and alloreactive recognition of graft cells
IL-2 – T cell proliferation and CTL activation
IFNg - DTH response, recruitment of Mf
increased MHC I and II expression (= more APC activity)
TNF-b – directly cytotoxic to graft cells
ADCC – although Abs are usually not as important as T cells
Which cell can be directly cytotoxic?
CD4 t cells
What are the three general categories of graft rejection I?
Acute- 2-4 weeks/ CTL and DTH/ differences in MHC genes
Hyperacute- occurs quickly/ due to pre existing antibodies/ ok NK cells (peoepl with repeated blood transfusions, women with many pregnancies, previous grafts)
chronic- takes months to years/ differenes in non MHC/ immunosuppressve drugs dont help/ many grafts eventually rejected
Immunosupresive drugs will not help?
How is graft survival acheived?
Blood type match
Minor histocomp. loci