Transplant Immunology Flashcards
What is an alloantigen ?
Antigen which varies between members of the same species
What is an alloreaction ?
Immune responses directed atainst alloantigens
What are immunogenetics ?
A subfield of immunology devoted to the genetics of alloantigens
What is an autograft ?
A graft of tiddue from one site to antoher site on the same individual
What is a Synergic graft ?
A graft of tissue from one individual to another individual that is genetically identical
What is an allograft ?
Graft of tissue from one person to another person that is genetically different
What are the three basic problems associated with transplantation of tissue ?
- It must perform its basic function
- Health of the donor and recipient must be maintained during the operation
- The immune system of the recipient must accept the transplantation
What are the most important genes involved with transplant rejection ?
The HLA haplotype
Do RBC’s express MHC-1 or MHC-2
No
What causes alleoreactions with blood transfusions ?
The alloreactions are based on the structural polymorphisms in the carbohydrates on glycolipids of the erythrocytes
What is the most common basis of alloreactivity to a graft produced by a recipients immune system ?
The difference in HLA expression on the erythrocyte surface. These differences are related to the A, B, O blood system
Is the blood surface glycoprotein similar to the surface antigen of bacteria ?
Yes. and because the surface carbohydrates are similar most people will have produced antigens specific
How would the body react against the foreign blood RBC’s
A person that has type O blood receives a transfusion of they A or type B blood that person’s Anti-A or Anti-B antibodies will attack the foreign blood types.
How is HLA polymorphic ?
There are many different alleles of the MHC class 1 molecule
What will happen if a person’s Anti-A or Anti-B antibodies bind to an RBC that they deem foreign ?
The Anti-A or Anti-B antibodies will activate the complement cascade and cause the Blood type. This will result in fever, chills, shock, renal failure, and sometimes death.
What is an Rh factor ?
A polymorphic blood antigen that are polymorphic with regard to the population
What is the most important Rh factor with regard to blood transfusion ?
The RhD factor
Is there any other antigen similar to the Rh antigen that the body could be sensitized to ?
No, unlike the ABO there are no structures on normal flora bacteria that are similar to the RhD. Therefore if people do not have Rh + blood they will not have an antibody sensitized to the Rh factor.
What would happen if an ( Rh - ) person was sensitized to the Rh factor receives blood from the ( Rh + ) donor
There would be life threatening blood reaction
Can a fetus have a different haplotype of MHC antigens from the mother.
Yes the fetus is essentially an allograft
What will happen if a mother (Rh-) gives birth of the baby who has a different Rh factor from her ?
The Rh - mother will be sensitized to the Rh factor and produce the Rh antibody. If the mother is exposed to Rh+ blood another time she will illicite the complement induced degradation of the blood that is foreign.
Does the placenta have MHC-1 on it ?
No it forms a barrier between the fetus and the mother’s T cells
Does the trophoblast express cytokines, If yes what do they do ?
Yes the tropoblast expresses cytokinesthat produce Th2 cytokines. They promote Ab responses and depress T cell responses.
When you have a woman who is Rh- and she has had a baby that caused her to be sensitized to the Rh factor how will you treat her if she is pregnant with another Rh+ baby ?
You give her Rhogam which is a preparration of Ab’s that are specific for RhD+ erythrocytes and will thus trigger their destruction.
