Chapter 17 - Transplants Flashcards
MATCHING:
1) autografts a) grafts exchanged b/w nonidentical members same sp.
2) isografts b) grafts exchanged b/w members of diff. species
3) allografts c) grafts exchanged from 1 part to another same body
4) xenografts d) grafts exchanged b/w identical twins
1 - c
2 - d
3 - a
4 - b
Graft rejection shows what 2 key features of adaptive immunity?
memory and specificity
what is graft rejection mediated by?
lymphocytes / T lymphocytes
what is common to all T-cells?
CD3
what HLAs are strong barriers to transplantation?
class I (HLA-A, HLA-B)
what are the 3 most important HLAs for transplantation?
class II (HLA-DP, HLA-DQ, HLA-DR)
remember it’s alphabetical p, q, r
in direct allorecognition, what does the T cell recognize?
what is it involved in?
UNPROCESSED allogeneic MHC from APC
primary response against graft
in indirect allorecognition what does the T-cell recognize?
when is this important?
PROCESSED peptide of allogeneic MHC molecule bound to self MHC or Professional APC
during chronic rejection when # of donor prof. APCs is low
what are the types of rejections in order from least time to most time taken
hyperacute, accelerated, acute, chronic
what is the cause of hyperacute rejection?
preformed antidonor Abs and complement
what is the cause of accelerated and acute rejection?
reactivation of sensitized T cells
primary activation of naive T cells
what is the cause of chronic rejection?
immunologic and nonimmunologic factors
Acute cellular rejection involves what?
Th1 cells
Acute vascular rejection involves what?
Th2 (humoral)
what kind of response does hyperacute rejection involve?
Humoral response
what is an example of hyperacute rejection?
what does it activate?
ABO blood group incompatibility
classical complement activation leading to death of epithelium
what is an example of acute rejection?
what kind of cell damage is present? by what?
CD4 and CD8 T cells occurs in days to weeks
parenchymal cell damage, interstitial inflammation, endothelialitis
by CTLs and DHT reactions
what plays an important role in triggering acute rejection?
Donor DCs (aka passenger leukocytes)
what is an example of chronic graft rejection?
what is involved and what pathway is the main pathogenic mech?
months to years after transplantation due to ischemia of the organ
macrophages and Abs involved, main mech is Indirect pathway
what are some non-immunological factors in chronic rejection?
does chronic rejection respond to immunosuppressive therapy?
ischemia-reperfusion damage, recurrence of the disease, nephrotoxic drugs
NO
what variables determine transplant outcome?
condition of the allograft (non-immunological factors)
donor-host Ag disparity
strength of host anti-donor response
immunosuppressive regimen
when transplanted, damaged graft tissues release mediators which trigger several biochemical cascades leading to what?
immediate tissue damage via a clotting cascade generates fibrin and fibrinopeptides
what do fibrinopeptides do?
increase local vascular permeability and serve as chemoattractant for neutrophils and macrophages
what does the kinin cascade produce?
what do early proinflammatory responses lead to if left uncontrolled?
bradykinin which causes vasodilation, smooth muscle contraction, and increased vascular permeability
allograft rejection
