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- - Functions as an immunological barrier between the mother and the fetus
- -Trophoblast cells provide nutrients to the embryo , develop into a large part of the placenta.Form tissues of the chorion
Tolerance of the Fetus
- -The fetus represents a foreign entity to the maternal immune system, because its semiallogeneic.
- -The immune system is altered to “tolerate” the fetus.
Maternal Immune Cells
Include:Macrophages, uNK cells(uterine natural killer cells), Helper T cells, Cytotoxic T, lymphocytes- prevent virus multiplication
-uNK cells ¯ophages regulate &balance trophoblast.
-A shallow amount of trophoblast or an over invasion of trophoblast is problematic to the mother- may cause preeclampsia
-The number of immune cells changes through out pregnancy.
-First trimester= abundance of uNK cells& macrophages
-Second trimester = Decrease in Cytotoxic T lymphocytes, regulatory cells and uNK cells and The decrease in these immune cells play a role in the acceptance of the fetus and the placenta.
•Killer cell immunoglobulin receptors are transmembrane glycoproteins expressed by all NK cells and T cells.
•The KIR2DL4 receptor activates NK cells.
•HLA-G accumulates in the KIR2DL4 endosome.
•HLA-G molecule inhibits immune response by blocking the receptor
The HLA-Gmolecule(human-leukocyte antigen)
- -Is a protein in humans that is encoded by the HLA-gene
- -Plays a role in immune tolerance in pregnancy
- -HLA-G is expressed by the trophoblast & it protects the fetus from decidual NK cell attack
- -Isoforms of HLA-G saturate the maternal-fetal interface & circulate in mothers throughout pregnancy
- -HLA-G proteins facilitate semiallogeneic pregnancy by inhibiting maternal immune response to foreign (paternal) antigens
- -HLA-G expression is restricted to the fetal trophoblast cells that invade the maternal decidua during early pregnancy.
Prone to Infection
-During pregnancy women are more prone to infection, because different immune cells are suppressed and others are enhanced in order to allow the developing fetus to live.
-The absence of T Cells puts women at a higher risk of viral infection, viral illness, as well as opportunistic infections
- Congenital Infections
- -infections that occur in the womb
- -infection can occur before the infant is born or during the birth process
- -affects babies as the result of infection of the mother during pregnancy
- -Toxoplasmosis- infection caused by a parasite, common host is the cat
- -Other infections-syphilis, varicella- zoster
- -Rubella- (German Measles)
- -Cytomegalovirus- CMV, herpesvirus family, can cause blurred vision& diarrhia.
- -Herpes simplex virus2- genital herpes
- Perinatal Infections
- -Acquired during labor
- -By exposure to anogenital secretions, and blood
ex: Herpes Zoster Virus(shingles), HIV, Hepatitis B Virus(HBV), Chlamydia
- Postnatal Infections
- -Acquired after birth
- -By direct contact or breastfeeding
ex: Meningitis, Pneumonia, UTI, Oral Thrush- yeast of the mouth,Conjunctivitis
§Maternal Infections spread to the embryo& fetus by ascending infection from the upper vagina via the uterine cervix to amniotic fluid or …….
Maternal infections can spread in a hematogenous matter as a result of maternal viremia, bacteremia, or parasitemia
If infection reaches the womb it can cause the chorion to become inflamed and infected, causing preterm labor.
Expecting mothers should consider being vaccinated prior to conception or postpartum
Vaccines prior to pregnancy- measles, mumps, rubella(German measles) vaccines
Vaccines during pregnancy(only if at high risk) -Tdap (prevents against whooping cough)
Inactive vaccine preferably