T1 L15 Intro to transplantation Flashcards
What is transplantation?
Grafting of tissue, usually from one individual to another
What is an autograft (autologous) transplant?
To another site on same individual e.g. after burns
What is an isograft?
(Iso/syngeneic)
To genetically identical individual (homozygous twins)
What is an allograft?
(Allogeneic)
To genetically disparate members of same species
What is a xenograft?
To a different species
What is the warm ischaemic phase?
Time from interruption of circulation to donor organ until organ is flushed with hypothermic preservation solution
What is the cold ischaemic phase?
While organ is preserved in hypothermic state prior to transplantation into recipient
What is the mechanism for hyperacute reaction?
Preformed antibodies
When does a hyper acute rejection occur?
Minutes to hours
Can be days
What is the mechanism for acute rejection?
T cells
When does an acute rejection occur?
Days to weeks
can have late acute
What is the mechanism for chronic rejection?
Chronic processes including vascular changes in the graft
When does chronic rejection occur?
Months to years
can be weeks
What are the 4 major blood groups?
A
B
AB
O
Who can Rh positive patients receive blood from?
Those who are Rh positive or negative
Who can those with group O receive blood from?
Only group O
Who can group O donate to?
Everyone
Who can group A donate to?
A
AB
What happens if someone with group O was given a kidney from a donor with blood group B?
Antibodies would bind to inside of blood vessels in the graft Complement binds Triggers complement cascade Coagulation of blood Occlude blood vessles Hyperacute rejection
Describe how HLA causes graft injury
Induce phenotypic changes in donor vasculature Causes endothelial cell (EC) activation --> promotes recruitment of leucocytes & CD4 T-cell proliferation in response to alloantigen HLA class II on endothelial cell Complement-activating antibodies trigger classical pathway through binding of C1q --> production of anaphylatoxins C3a & C5a --> potential to directly augment leucocyte recruitment & T-cell alloresponses Monocytes, neutrophils & natural killer cells express Fc receptors (FcyRs) which can interact with heavy chain of HLA antibodies bound to donor ECs
How is hyper acute rejection prevented?
Matching donor and recipient for HLA and ABO blood group antigens using PCR
How are HLA antigens cross matched?
Incubation of washed donor cells with recipient serum
Antibody-binding detected by mouse-anti human Ab stain of recipient cells or cytotoxicity
Where are class I MHC molecules found?
On all nucleated cells
Where are class II MHC molecules found?
On subset of nucleated cells
