Immunology and Pregnancy
• Why is the immune system relevant to pregnancy?
o The foetus is an allograft
▪ Cells are different to the mother’s cells
o The woman’s immune system ignores “self” cells but rejects/ kills “non-self”
cells
▪ Foetus is genetically dissimilar to the mother so why isn’t it rejected like
a transplant?
• Allogeneic means genetically different
o Syngeneic mean genetically identical
• Pregnancy is similar to an organ transplant
o When a recipient receives a transplanted organ from a genetically different
donor, the organ is destroyed, or immunosuppression is required
o More likely to get an organ transplanted from someone who is genetically
different from you unless you are an identical twin
o Mechanisms of rejection include:
▪ T cells- T helper (Th) cells and Cytotoxic T Lymphocytes (CTLs)
▪ Antibodies
▪ Natural Killer (NK) cells
▪ Innate effector cells- macrophages, neutrophils etc.
• The immune system has two arms
o Innate- cells and molecules that recognise “danger” pathogens or damage
▪ Kills immediately after infection
▪ Lack versatility to different pathogens
▪ Examples include NK cells, macrophages, neutrophils and complement
▪
o Adaptive- cells that recognise “non-self”
▪ Have more versatility than innate immune system
▪ Requires the immune system for activation
▪ Slow at first encounter (primary response) but has memory and can
respond much faster and more effectively on subsequent exposures
(secondary response)
, ▪ Examples include T and B cells and antibodies
▪
• B cell receptor (BcR)
o B cells recognise soluble antigens
▪ An antigen is an Antibody-generating molecule
• Anything the adaptive immune system recognises as “non-self”
o B cells produce antibodies and have antigen-specific receptors (BcR)
▪ Antigen binding region is made in an entirely random way
• Made by somatic recombination
• >1018 different specificities
o Each B cell has a unique specificity
o During development the random antigen specific receptors that bind to self-
antigens are deleted/killed
▪ Type of negative selection
o When antigen-specific B cells are activated, they produce antibody
▪ Once activated, they are known as a plasma cell
▪ An antibody is a soluble version of the BcR
▪ Binds to pathogens/ foreign tissue- targets them for killing
▪
• T cell antigen recognition
o T cell receptor (TcR) is analogous to antigen-binding region of an antibody/BcR
▪ However, it cannot bind soluble antigen directly
▪
• Why is the immune system relevant to pregnancy?
o The foetus is an allograft
▪ Cells are different to the mother’s cells
o The woman’s immune system ignores “self” cells but rejects/ kills “non-self”
cells
▪ Foetus is genetically dissimilar to the mother so why isn’t it rejected like
a transplant?
• Allogeneic means genetically different
o Syngeneic mean genetically identical
• Pregnancy is similar to an organ transplant
o When a recipient receives a transplanted organ from a genetically different
donor, the organ is destroyed, or immunosuppression is required
o More likely to get an organ transplanted from someone who is genetically
different from you unless you are an identical twin
o Mechanisms of rejection include:
▪ T cells- T helper (Th) cells and Cytotoxic T Lymphocytes (CTLs)
▪ Antibodies
▪ Natural Killer (NK) cells
▪ Innate effector cells- macrophages, neutrophils etc.
• The immune system has two arms
o Innate- cells and molecules that recognise “danger” pathogens or damage
▪ Kills immediately after infection
▪ Lack versatility to different pathogens
▪ Examples include NK cells, macrophages, neutrophils and complement
▪
o Adaptive- cells that recognise “non-self”
▪ Have more versatility than innate immune system
▪ Requires the immune system for activation
▪ Slow at first encounter (primary response) but has memory and can
respond much faster and more effectively on subsequent exposures
(secondary response)
, ▪ Examples include T and B cells and antibodies
▪
• B cell receptor (BcR)
o B cells recognise soluble antigens
▪ An antigen is an Antibody-generating molecule
• Anything the adaptive immune system recognises as “non-self”
o B cells produce antibodies and have antigen-specific receptors (BcR)
▪ Antigen binding region is made in an entirely random way
• Made by somatic recombination
• >1018 different specificities
o Each B cell has a unique specificity
o During development the random antigen specific receptors that bind to self-
antigens are deleted/killed
▪ Type of negative selection
o When antigen-specific B cells are activated, they produce antibody
▪ Once activated, they are known as a plasma cell
▪ An antibody is a soluble version of the BcR
▪ Binds to pathogens/ foreign tissue- targets them for killing
▪
• T cell antigen recognition
o T cell receptor (TcR) is analogous to antigen-binding region of an antibody/BcR
▪ However, it cannot bind soluble antigen directly
▪
