Transplantation Flashcards
What are the 2 immunogenic responses you have to worry about during transplant?
Transplant rejection= host v graft (when recipient’s T cells attacks foreign tissue)
Graft v. host rejection (when marrow transplant –> T cells that attack recipient)
Define autologous, syngenic, allogenic, xenogenic
Autologous = from self
Syngeneic = from identical twin
Allogenic = from a genetically different individual from same species
Xenogenic = from different species
What are the risks of immunosuppressive drugs?
Toxicity
Risk of opportunistic infection
Loss of surveillance against malignancies
What component is most important to match between donor/recipeint?
HLA
What is the main response in organ allograft rejection?
How do you treat it?
T cell dependent
Treat with immunosuppressive drugs + steriods during acute episodes
Chronic rejections still occur despite advances in immunosuppressive drugs
What is a hyperacute reaction?
Where do the antibodies that do this reaction come from?
Hyperacute = antibody mediated, with preexisting antibodies; can be prevented by selecting the right match
Types of antibodies = can be do to ABO mismatch (anti-ABO= natural, depending on recipient’s blood type) and presensitized due to anti-HLA (not natural, develop during pregnancy, transfusion, previous transplants)
It’s also a barrier to xenotransplantation – anti-Gal antibodies are natural
What is direct allorecognition?
It’s when CD4 and CD8 both recognize the donor DC via MHC II and I respectively
Very strong response– stronger than an ordinary immune response because it uses T cells that recognize antigens (bc there’s only negative selection against self antigens in thymus) = a cross reaction
What is indirect allorecognition?
Recipient DC presents peptide derived from donor cell to CD4. CD4 stimulates B cells to make antibodies against donor cell.
Weaker response, more like a normal response to antigen
This response is responsible for chronic rejection of organ transplants.
How do corticosteroids prevent rejection?
Inhibit T cell activation, kill proliferating cells
Modify the TCR mediated signaling pathway by reducing NFAT activation, at TF that leads to cytokine production
How does immunosuppressive therapy prevent organ rejection?
Antibodies specific for T cells prevent/control acute rejection
What is a hematopoietic cell transplantation (HCT)?
“bone marrow” transplant
but it can also use mobilized peripheral blood
Treat genetic diseases of bloodc cells (leukemias, lymphomas)
Remember it’s alloreactions from marrow transplant that attack the patient, not the other way around
What is a minor histocompatibility antigen?
A polymorphic peptide that is presented by a MHC
These are responsible for differences between donor and recipient & why you can never have an exact match between donor & recipient
