Fetal & Neonatal Immunity Flashcards
why is the fetus considered an “allograft”
it is a tissue transplant that contains MHC genes that are “non-self” relative to the mother
- has maternal and paternal MHC
how does the presence of non self MHC on the fetus not trigger an immune response by the mother
it is a site of immune privilege
has specialized cells that allow for the fetus to persist throughout gestation
trophoblasts
fetal cells that line the outermost layer of the placenta
major barrier between fetal compartment and maternal blood
how do trophoblasts prevent an immune response from the dam
do not express MHC II proteins
usually do not express MHC I proteins, but if they do it is non-classical
what is a risk of having the maternal-fetal interface be immune privileged
pathogens that are not cleared from the body are able to colonize the area due to low MHC expression
decidual NK cells (dNK)
largest population of maternal immune cells
involved in maintenance and tissue remodeling for fetal invasion during implantation
- NOT cytotoxic
- produce growth factors, angiogenic factors, and cytokines
decidual macrophages
primary APCs at the maternal-fetal interface
- anti-inflammatory: express IL-10
- promote vascular growth by producing VEGF and MMP9
- promote clean up and phagocytosis of apoptotic trophoblasts
- produce IDO to prevent T cell activation and dampen immune response
fetal-specific Treg cells
confer tolerance to fetal antigen and help maintain a homeostatic environment for fetal survival
recruited to and induced at the maternal-fetal interface
is the maternal immune system aware of the fetus or does the fetus evade it completely/go undetected
maternal immune system is AWARE and induces a tolerance response with Treg cells
dam is NOT immunosuppressed
what immune responses are altered in the dam during pregnancy
Th1: improves with pregnancy
Th2: worsens with pregnancy
how does gestation length impact immunocompetence of the neonate
longer gestation = born with fully developed immune system
shorter gestation = immune system still developing after birth
at what day in gestation does the fetus begin to produce its own antibodies
day 125
produces IgG
effect of infection with BVDV during early gestation (<125 days)
cow becomes immune
fetus becomes tolerant –> does NOT produce antibody against it
calf will be infected for life but is antibody negative –> becomes a continuous shedder
virus may mutate into a cytopathic form causing superinfection of calf and other viremic animals leading to fatal mucosal disease
effect of infection with BVDV in mid gestation (100-150 days)
calf has congenital malformations
effect of infection with BVDV in late gestation (>150 days)
calf is normal and has protective antibodies
