4. immunology of pregnancy

Question 1

what immune cells are located in the maternal-fetal interface (placenta)?

Answer 1

uterine NK cells (70%), macrophages (20%), T-cells (CD4+, CD8+, - T-cells, Treg) (10%), dendritic cells, and B cells (few).
The number of these cells and the roles they play differ throughout the various stages of pregnancy.

Question 2

what local and systemic mechanisms are involved in protecting the developing fetus from attack by the maternal immune system?

Answer 2

1. cytokine shift
2. influence of female sex hormones
3. HLA expression by trophoblasts

Question 3

what is the two main purposes of the innate immunity in pregnancy?

Answer 3

1) provides continuous host defense against infections
2) interacts with fetal tissues to promote placentation and fetal growth.

innate immunity remains intact

Question 4

what is the cytokine shift that occurs during pregnancy to protect the fetus from the maternal immune system?

Answer 4

↑ regulatory adaptive immunity (dominance of TH2-type immunity–successful pregnancy).
↓ cytotoxic adaptive immunity (induction of TH1-type responses– dangerous)

Question 5

what influence do female sex hormones have during pregnancy to protect the fetus from the maternal immune system?

Answer 5

estrogen and progesterone play immunomodulatory functions, affecting immune cell recruitment, expansion, and function.

Question 6

what exactly is the HLA expression by trophoblasts that occurs during pregnancy to protect the fetus from the maternal immune system?

Answer 6

Trophoblasts exhibit unique MHC expression- HLA-C, E, F, and G (of the MHC class I type) 
they control the depth of trophoblast invasion and bind to inhibitory NK cell receptors.

Question 7

what is immunologic evasion of semi-allogenic fetus by the mother?

Answer 7

fetus/placenta expressing both self (maternal) and nonself (paternal) genes

Question 8

when are macrophages developed ?

Answer 8

week 4- macrophage-like cells arise from the yolk sac

week 16- fetus has the same number of circulating macrophages as adults (but less functional)

Question 9

what week are Immature granulocytes found in the fetal spleen and liver?

Answer 9

week 8

Question 10

when are T-cells first seen in the blood islands of the yolk sac?

Answer 10

8 weeks

Question 11

when is B-cells first detected in the liver?

Answer 11

8 weeks

Question 12

what type of Maternal Ig crosses the placenta?

Answer 12

IgG (late 1st trimester)
but the efficiency of the transport is poor until 30 weeks
*transfer passive immunity to the fetus

Question 13

why can’t IgM cross the placenta?

Answer 13

because of it’s large molecular size

Question 14

when are IgG, IgA and IgM secreted?

Answer 14

IgG, IgA: during 2nd trimester

IgM: 3rd trimester