Leslie's "Fetal immune system husches attack on maternal cells" 2010

From Biol557

• During pregnancy, the baby really does receive some of mom's cells that sneak through the placenta.
• And now we have an explanation for why these stow-aways are not attacked by the baby's immune system.
• This explanation also suggests a new mechanism for how the body generates self-tolerance.
• Cells from the mom that make it into the fetus stimulate the production of regulatory T cells or T reg cells.
• T reg cells dampen the immune response and may be a source of the body's ability to not attack its own cells.
• Studies show that cells cross both ways over the placenta and fetal cells can reside in the mother for decades and maternal pancreatic cells are more likely to be found in children with type I diabetes than those without.
• Fetal immune system is hard to study because the mouse model of immunity doesn't mature until after birth.
• Some researchers have looked at the lymph nodes of 2nd trimester babies and found a higher occurrence of maternal cells than ever believed to be likely before.
• So, if as has been shown, fetal immune cells can respond to cells from other adults, why don't fetal immune cells respond to maternal invaders?
  • Researchers propose that the fetus uses the same mechanism as the mother, T reg cells depress the immune response.
  • There is evidence for this, too. When T reg cells were removed from fetal lymph nodes harboring fetal lymphocytes and maternal invaders, there was a strong reaction against the invaders.
• So the authors propose that use of T reg cells could also depress self reactions which would be a gentler way to inhibit these reactions than the already-known-about mechanism of killing off lymphocytes that respond to host antigens.
• All this evidence strengthens the argument that the fetal immune system, while not fully developed at birth, can put up a fight and is more developed and capable than previously believed.
• We should research the use of T reg cells because:
  • T regs tuned to the maternal type have been found in children as old as 17,
  • T reg cells may be useful for making transplants work better, and
  • T reg cells may be responsible for some infant vaccination failures.