MHC and Transplantation Flashcards
In what cells do blood group substances fluoresce?
All vascular enodthelial membrane, some epithelial cells.
What two types of isoagglutinins are there?
A or B
What is an isoagglutinin?
An isoantibody capable of gluing together cells from individuals of same species.
In whom is MHC found?
All vertebrae species
How many MHC molecules are found in an average mammalian cell?
50-100,000
What 4 functions does an MHC molecule have?
> Immune role
Histocompatibility
Reproductive role
Disease susceptibility
Where are MHC molecules expressed?
At the cell surface
What do MHC molecules present?
Self and non-self antigens to T cells.
On what chromosome and what position is the Human MHC (aka HLA complex) found?
Chromosome 6, position 21.3.
How many bp is the human MHC?
3.6Mbp
What antigens do Class 1 MHC encode?
HLA-A, B, C = CLASSICAL
What antigens do Class 2 MHC encode?
HLA-DR, DQ, DP
Where are Class 1 MHC antigens present?
On all nucleated cells
Where are Class 2 MHC antigens present?
Mostly B lymphocytes, can induce on T lymphocytes.
What is Class 1 MHC heavy chain non-covalently associated with?
B2 microglobulin
What is Class 2 MHC a chain non-covalently associated with?
B chain
What type of inheritence does MHC follow?
Mendelian
At a given locus how many antigens does an individual inherit?
2 antigens
What type of expression does MHC follow?
Co-dominant expression- all antigens express on cell surface
At each locus, what makes MHC polymorphic?
Lots of allele variants
What is the advantage of MHC polymorphism?
It allows greater chance of mounting immune response against antigen.
What antigen is broad in HLA nomenclature?
A19
What does ‘split’ mean in HLA nomenclature?
A19 has subgroups.
What HLA type is denoted by an asterisk and 4 digits?
Molecular
What is direct recognition in transplantation?
> Donor WBC interact with recipient T cell
T cell recognise non-self antigen
T cell proliferate –> damage graft.
When does direct recognition occur?
Immediately on transplantation
What is indirect recognition in transplantation?
> Recipient WBC interact with foreign protein
Self T cells break it down
Damage graft
Define: Sensitisation
Any event that leads to a HLA directed immune response.
What are 3 examples of sensitisation?
> Pregnancy
Transplantation
Blood transfusion
Define: Calculated Reaction Frequency
The percentage of donors in the last 10,000 that are unavailable to the recipient
What 3 things does a pt’s transplant chance depend on?
> Their blood group
The rarity of HLA type
Extent of sensitisation
What is a hyperacute rejection?
When recipient anitbodies in their blood bind to the graft enothelium.
What is activated in a hyperacute rejection?
> Complement
> Clotting cascade
What is the result of a hyperacute rejection?
Endothelial integrity reduced (leaky)
What can result from a hyperacute rejection?
DIC –> ~death
What does a Flow cross match detect?
If there are antibodies in pt’s serum against donor HLA antigens.
