Neonatal Immunity Flashcards
Innate Immunity
Initial resistance to infections from birth
How is the adaptive immune system for animals with a long gestation period?
Adaptive immune system is fully developed at birth but can’t function at adult levels for several weeks
How is the adaptive immune system for animals with a short gestation period?
Adaptive immunity is less developed @ birth
Development of the immune system
- B cells appear soon after development of spleen and LNs (no antibodies until late fetal life)
- Ability to respond to antigens develops rapidly after lymphoid organs appear
- Serum of newborn animals is deficient in some complement (more susceptible to infection)
When are neutrophils capable of phagocytosis?
@ 90 days post-conception in fetal pigs
How is immune response shown in serum of newborns?
By lymphoid hyperplasia and elevated immunoglobins (suggest infection in embryo)
What does immune response depend on in the fetus?
On the state of immunological development (days of gestation)
Bluetounge in ewes
Disease @ 50 days causes severe disease in fetal lambs
@ 100 days only causes mild disease
Parvovirus for piglets
Before 55 days of gestation it’ll cause abortion or still birth in piglets
After 72 days piglets will develop antibodies to parvo to survive
What does the transfer of immunity depend on?
The type of placenta
Placenta of primates, rodents and humans?
Hemochorial placenta
Maternal blood is in direct contact with trophoblast
Allows transfer of IgG
Placenta of dogs and cats
Endotheliochorial
5-10% of IgG may transfer to fetus
Most obtained through colostrum
Placenta of ruminants
Syndesmochorial
No trans-placental transfer of Igs
Newborns receive maternal Igs through colostrum
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Placenta of Horse and pigs
Epitheliochorial
No trans-placental transfer of Igs
Newborns receive maternal Igs through colostrum
Colostrum
Contains accumulated secretions of mammary glands over the last few weeks of pregnancy with proteins from the blood
What is colostrum rich in?
IgG and IgA
Lymphocytes and cytokines
What is the predominant Ig in colostrum in domestic animals?
IgG
Composition of colostrum and milk in humans and primates
IgA predominates
Composition of colostrum and milk in dogs, pigs and horses
IgG in colostrum
IgA in milk
Composition of colostrum and milk in cats
IgG in colostrum
More IgG than IgA in milk
Composition of colostrum and milk in ruminants
IgG1 in both
What happens to colostrum after absorption?
Colostrum proteins aren’t degraded
IgGs bind to receptors (FcRn) on intestinal epithelial cells then absorbed into blood
When is gut permeability for absorption of Igs the highest?
Immediately after birth, declines after 6 hrs
Neonatal Fc receptor (FcRn)
Prevents IgG degradation
Recycling of IgG and maintaining IgG levels