Fetal Transplant Flashcards
Self-to-self transplant
Autograft
Identical twin-to-twin transplant
Isograft
Person-to-person transplant
Allograft
Species-to-species (strong rejection)
Xenograft
Primary cells in transplant rejection
Th1, Th17, CD8, NK, INF-gamma, macrophages, IL-2 and 21, IL-4
Intimal thickening leading to graft ischemia
Chronic rejection
Overall way to induce tolerance
Manipulate Tregs
Specific ways to induce tolerance
Provide inhibitory second signals (CTLA-4), T regulatory cells (CD4, 25) or cytokines (Il-21, IL-23, IL-10 & TGF-beta) to override Th1, Th17 and CD8 responses
How do Tregs suppress rejection?
Tregs suppress/kill recipient T cells that don’t recognize graft/try to attack it
Recipient T cells attack transplant
Organ transplant
T cells in transplant attack recipient’s tissues
Bone marrow transplant
GVHD
Graft vs. host disease
can occur in immunoincompetent patients receiving transfusions (rxn w/ lymphocytes)
Reason why xenografts are ineffective
α-1,3 GT
- Primates deleted this gene a long time ago, and developed an anti-α-1,3 GT in response to gut bacteria
- Lots of other animals still make α-1,3 GT
Also, xenovirus transmission is an issue
Complex presented by trophoblastic (fetal) tissue at maternal-fetal interface
“public”
MHC HLA-G
*NO DISPLAY OF MHC I OR II
Characteristics of pregnant uterine NK cells
Inhibited by MHC HLA-G
No FcR displayed
Produce angiogenic factors to support placenta
Role of maternal γδ T cells
Hone to uterus, promote tolerance to fetus
maternal T lymphocytes (ly) come in contact with fetal ly (maternal & paternal MHC) at the placental interface maternal ly or in the fetus itself, ____________
They are converted by fetal TGF-beta to paternal specific T-regs
______ promotes display of DAF on uterine cells
*Decay accelerating factor is a regulator of complement system
Progesterone
Spontaneous abortion may result from this
Failure of maternal ly conversion to paternal specific T regs at the placental interface
This T-cell group promotes success of pregnancy, but may increase risk of intracellular infections
Th2
- also Tregs
T-cell group associated with decreased success in pregnancy
Th1 bias
