Immunogenetics and Transplant Flashcards
What is the MHC or HLA?
MHC= Major Histocompatibility Complex HLA= Human Leukocyte Antigen
It is a region of genes that encode for proteins that are involved in antigen presenting.
In which cells do we find Class II MHC (HLA)?
Dentritic Cells
Macrophages
B-cells
In which cells do we find Class I MHC (HLA)?
All
Why is HLA-DR important?
It is the most expressed class II gene on surfaces of cells and important for transplants
What are the most important/expressed HLA s in class I?
A and B
Why are transplants so difficult with respect to HLAs?
There are so many polymorphisms in HLA genes because of the gene duplication that happened.
What is a haplotype?
The set of alleles at a group of linked loci (no recombination).
I.e. the specific genes you inherit from 1 parent.
What are the different genes in the HLA class II?
DP DQ DR
As a group it is also known as HLA-D
What are the different genes in the HLA class I?
A, B, C
A father’s HLA phenotype is A1, A3, B5, B7, DR9, DR11. The mother’s phenotype is A2, A4, B6, B8, DR10, DR12. They have had a baby whose phenotype is A1, A4, B6, B7, DR11, DR12. What are the father’s, mother’s and child’s haplotypes?
Father-A1,B7,D11 & A3,B5,DR9
Mother- A4,B6,D12 & A2,B8,D10
Child- A1,B7,D11 & A4,B6,D12
A father’s HLA phenotype is A1, A3, B5, B7, DR9, DR11. The mother’s phenotype is A2, A4, B6, B8, DR10, DR12. They have had a baby whose phenotype is A1, A4, B6, B7, DR11, DR12. Could they have a child who is A1, A2, B7, B8, DR10, DR11? or A3, A4, B5, B8, DR9, DR12?
Father-A1,B7,D11 & A3,B5,DR9
Mother- A4,B6,D12 & A2,B8,D10
A1, A2, B7, B8, DR10, DR11? Yes
A3, A4, B5, B8, DR9, DR12? No
Who is the best possible donor for a patient needing a transplant?
Siblings
There is a 1/4 chance they have the same HLAs as you.
How does MLR work and what is it used for?
- Collect WBC from donor and patient.
- Radiate WBC from donor to kill Tcells. (not transplanting T-cells)
- See if patient T-cells react against donor monocytes.
Which class of HLA do Th1 cells recognize?
Class II only
Describe the cellular and molecular events which go on during graft rejection, including cytotoxic T cells, Th1 cells, and macrophages
- Host Th1 cells recognize Class II HLA on transplanted macrophages or DC.
- Activated Th1 secretes IFN-y and recruits host Macs.
- Also secretes IL-2 which recruits CTLs.
What is alloreactivity? And what role does it play in transplants?
Alloreactivity is the immune reaction that occurs between members of the same species.
Your own Tcells are activated by something that looks “not quite like you.” This can be your MHC + antigen, or someone else’s MHC + antigen.
How do autoimmune diseases and HLA alleles relate?
Every autoimmune disease is associated with a specific HLA-allele.
Ex. Diabetes type I and DQ2 and DQ8
When do hyperacute rejections occur?
When the recipient has a preexisting antibody IgG or IgM against the donor tissue in some way.
