Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
what is a autologus graft?
|
self to self
|
|
|
what is a syngeneic graft/isograft?
|
between genetically identical twins
|
|
|
what is a allograft?
|
between two different people in same specifies
|
|
|
what is a xenograft?
|
between different species
|
|
|
what are most transplants done today?
|
allografts- between two people of the same species
|
|
|
what are alloantigens?
|
foregin antigens on the surface of transplanted cells/tissues
|
|
|
What are alloreactive cells?
|
these are the cells that react against alloantigens (transplanted tissue)
|
|
|
what histocompatibilties elicit strong responses? weak ones?
|
Major histo= strong
minor histo= weak |
|
|
what is a haplotype?
|
this is the set of MHC alleles on each chromosomes, and each person has TWO haplotyes!
|
|
|
what is indirect presentation of alloantigens?
|
this is where recipients APC's present peptides from the graft
|
|
|
what is direct presentation of alloantigens?
|
this is where donor APC's present peptides from the graft
|
|
|
What does an allogenic MHC with a bound peptide mimic?
|
the determinant of a self MHC and foregin peptide. - this will illicit a strong immune response
|
|
|
what cells play a role in chronic rejection?
|
alloreactive T helper cells
|
|
|
what cells play a role in acute rejection?
|
alloreactive CTLs (cytotoxic lymphocytes)
|
|
|
What is the time frame for hyperacute rejection? how does it work?
|
this begins within minutes to hours.
mediated by preexisting antibodies in the recipient against alloantigens on endothelial cells of graft |
|
|
What are common alloantigens in hyperacute rejection? what are they usually from?
|
these are antibodies against ABO blood groups/MHC molecules
usually from previous exposure to alloantigens |
|
|
What is the method of hyperacute rejection reacting to an allograft?
|
host antibodies bind the alloantigens, and activate compliment, attacting neutrophils.
these then damage the membrane and clots can form |
|
|
What is the method of action of acute rejection? what cells are responsible? when?
|
this can occur as early as 7-10 days after transplant (but usually within 2 months)
cause by T cells binding to MHC's of the vascular walls in the transplant organ |
|
|
What is the hallmark of acute rejection?
|
activated T cells killing the graft cells.
|
|
|
what is used to prevent rejection (before the transplant occurs)
|
HLA typing and crossmatching test
|
|
|
What defines chronic rejection? what causes it?
|
loss of graft function over months to years.
result from fibrosis and occlusion of small arteries and arterioles |
|
|
What are the two mechanisms of action of chronic rejection?
|
increased fibrosis and chronic inflammation from Th1 cells
Smooth muscle proliferation, lymphocytes and macrophage promote smooth muscle cell growth. both cause reduced blood flow |
|
|
How do cotricosteroids prevent graft rejection?
|
they suppress inflammation
inhibit IL-1 from APCs (which turns on helper T's) also inhibits MHC expression |
|
|
How do mitotic inhibitors prevent graft rejection?
|
these agents inhibit the biosynthesis of nucleic acid
|
|
|
What are the two general immunosuppressive therapies?
|
coritcosteriods and mitotic inhibitors
|
|
|
What are the non antibody specific immunosuppressive therapies? how do they work?
|
IL-2/ IL-2R inhibitors
IL-2 action blockers. these reduce the activation of T cells (Helper T's-> IL-2-> cytotoxic T's) |
|
|
what are the antibody based specific immunosuppressive therapies?
|
Polyclonal anti-thymocyte antibodis
Monoclonal anitbodies against CD3, CD25, CD52 CD3= t cells CD25= IL-2R CD52= mature lymphocytes |
