immu3202 Flashcards
How true is the fact that the mother’s immune system does not come into direct contact with the foetus?
Not particularly true.
The blastocyst implant in the endometrium to form what is called the decidua.
The placenta that develops anchors onto decidua and directly contact maternal blood and facilitate exchange of nutrients, gases and wastes.
Why doesn’t the immune system attack the placenta?
1) Different HLA expression. Placenta only express HLA-C. Because CD4, and CD8 usually only recognise HLA-A and B, they are not going to attack the placenta.
The placenta itself can secrete FasL and TRAIL which can cause apoptosis of activated T cells.
The placenta can produce “tolerogenic” molecules like IDO. IDO is present on the maternal-fetal interface, including trophoblast, decidual stroma and decidual immune cells which could help degrade tryptophan and prevent T cell proliferation.
Maternal decidual cells silence T cells attracting chemokine genes
What are the roles of dNK cells in pregnancy?
dNK are decidual natural killer cells.
They have the largest population in early pregnancy.
They are crucial in remodelling the decidua and spiral arteries
What are the roles of macrophages in pregnancy?
M1 macrophages-remodelling of spiral arteries for implantation and role in parturition
M2 macrophages: production of IDO; clean up of apoptotic trophoblasts
T cells role in pregnancy
There is a balance between Th1, Th2 and Th17 and Treg needed for pathogen defense
Specifically what are the roles of Treg in pregnancy?
They contain the inflammatory processes of implantation and parturition
They promote tolerogenic/anti-inflammatory phenotypes of DCs and macrophages
They restrain effector T cells
Is pregancy like a graft-host relationship [
Is the graft (foetus and trophoblast cells) constantly trying to ward off an attack from maternal immune cells?]
Placental trophoblast cells actively recruit immune cells to the maternal-fetal interface to facilitate implantation and promote successful pregnancy
Immune cells are co-opted to mediate tissue homeostasis
Immune cells maintain immune tolerance while still protecting against infectious agents.
Antiphospholipid syndrome
blood clots in bodies due to lots of autoantibodies and kid gets starved of nutrients and die
Haemolytic disease of fetus and newborn
RhD antigen (negative or positive blood type) is highly immunogenic
Imbalance of immune cells in pregnancy failure
Treg and dNK levels have been implicated in infertility/miscarriage
What is NK cell immunotherapy made from
prednisolone and clexane
IVIg
Intralipid infusions
What are the controversies of NK immunotherapy
no consensus on what an elevated levle of NK cells is
No evidence about what NK cells do-no evidence of NK cells actually attacking foetus
The treatment is not specific to NK cells
Treatment continues into first trimester of pregnancy so we don’t know what the safety for the foetus is
Why we still think NK immunotherapy is useful
subsets of pNK cells relevant to pregancy are being discovered. For example, TIM 3 pNK cells found to have an immunoregulatory role and were abnormal in women with miscarriage.
From what week in gestation does haematopoiesis shift from the yoke sack to fetal liver
week 5
At about week 5 of gestation, what immune cells are produced
ILCp, LTi, NKp, macrophages, mast cells
