L15: Immunity in the fetus and newborn

physical barrier against pathogens

the placenta's structural integrity serves as a ___ ___ ___ ___

prevent the mother's immune system from rejecting the genetically distinct fetus

what is the primary goal at the maternal-fetal interface called fetal tolerance?

attack foreign cells

the placenta actively suppresses the mother's cytotoxic adaptive immune responses which would normally...

a system of regulatory immune responses is promoted at the maternal-fetal interface, fostering tolerance and preventing inflammation

what is enhanced regulatory immunity?

gestational immune system development

in BVDV, the outcomes of infection are based on

persistent infection

a state where the host does not recognize the virus as a foreign antigen

continues to replicate in the host

in a persistent infection, an immune response does not occur, and the virus...

a reservoir of infection

what do persistently infected animals serve as?

embryonic death

what does infection during early pregnancy or pre-implantation lead to ?

high risk of fetal death, abortion, mummification, or development of persistenlty infected calf

what does infection during the first trimester before 125 days of gestation lead to ?

mature fetal immune system is more effective, so transient infection and calf born with BVDV specific antibodies

what does infection after 150 days of gestation lead to?

syncytiotrophoblasts

which layer of the placenta forms a highly differentiated layer of the placenta the that serves as a crucial interface between the mother and fetus?

1. resistant to toxicity

2. contributes to antigen masking by negative charge mucopolysaccharides

3. absence of class 1/2 MHC antigens

4. non-specific immunosuppression

5. antigen sink for absorbing MHC antibodies on placental cells

what are the functions of the syncytiotrophoblast layer?

the fetus can develop properly and not recognized as foreign in the dam.

the collective functions of the syncytiotrophoblasts downgrades the immune response so ...

epitheliochorial placenta

placenta where trophoblast cells of the placenta are in direct apposition with the surface epithelial cells of the uterus, no trophoblast-cell invasion beyond this layer

endotheliochorial placenta

placenta where the uterine epithelium is breached and trophoblast cells are in direct contact with endothelial cells of maternal uterine blood vessels

hemochorial placenta

placenta where maternal uterine blood vessels are infiltrated by trophoblast cells causing rupture and release of blood into the intervillous space

hemochorial

what type of placenta allows extensive gestational transfer of maternal immunoglobulins?

small amounts of IgG

in an endotheliochorial placentation, there is no contact with the syncytiotrophoblast and what can cross the placental endothelial barrier?

come in direct contact with maternal connective tissue of the uterus

preventing gestational transfer of maternal antibodies

in syndesmochorial placentation, the maternal epithelium is eroded, allowing the fetal chorion to....? what does this thick layer of epithelial cells and CT prevent?

primates and mice

examples of animals with hemochorial placenta

dogs and cats

examples of animals with endotheliochorial placenta

horse, cow, pigs, and marine mammals

examples of animals with epitheliochorial placenta

via yolk with IgY with IgA found in the egg white/albumin

how are maternal antibodies transferred in birds?

colostrum

the first secretion from the mammary glands after giving birth, rich in antibodies

FALSE!!! joiner will be mad at you

T/F: colostrum is the same as milk

that of serum

what do the antibody levels and isotype of colostrum resemble?

10 to 1000x more in colostrum

how do the antibody levels in colostrum compare to those in milk

transplacental: 90%

colostrum: 10%

what is the importance of transplacental vs colostrum antibodies in hemochorial placenta?

transplacental: 10%

colostrum: 90%

what is the importance of transplacental vs colostrum antibodies in endotheliochorial placenta?

transplacental: 0%

colostrum: 100%

what is the importance of transplacental vs colostrum antibodies in epitheliochorial placenta?

after 12 hours on 50% absorption rate and negligible after 24 hours

how does an animals ability to absorb colostrum change within hours of birth?

antibodies present in colostrum bottom out + loss of Brambell receptors (FcRn)

why is there a decline in colostrum absorption ability hours after birth?

Brambell receptor or neonatal Fc receptor

immunoglobulin G receptor that facilitates the transport of IgG from maternal milk into the bloodstream of neonates for passive immunity

protects it from degradation through pH dependent binding mechanism

how does FcRn play a role in maintaining serum IgG levels?

IgG from the intestinal lumen (binding state) via endocytosis to the extracellular space (release state)

the property of FcRn binding in a pH dependent manner permits FcRn to efficiently transport...

passive immunity

the short-term immunity which results from the introduction of antibodies from another person or animal

active immunity

the immunity which results form the production of antibodies by the immune system in response to the presence of an antigen

15 weeks, active immunity develops from birth to 15 weeks

while maternal antibodies are exteremely protective, they decline and are not detectable after...

increase of actively produced antibodies so total neonate immunoglobulin levels are stable

the decline of maternal antibodies usually coincides with ...

1. breed

2. first lactation

3. dams disease history

4. volume of colostrum produced

5. seasonality

6. environmental conditions

what are some factors that influence IgG levels in colostrum

50mg/mL or more IgG

what is considered high quality colostrum?

in newborn foals/calves when they don't receive enough maternal antibodies from colostrum → compromised immune system and increased risk of fatal infections

when does failure of passive immune transfer (FPT) occur?

1. production failure

2. ingestion failure

3. absorption failure

common causes of failure of passive transfer?

SNAP ELISA Foal IgG test using serum or whole blood

what can be used to test for IgG levels in foals for FPT?

1. if color of sample spot is darker than the 800mg/dL spot, the level of IgG in foal is more than 800mg/dL

2. if color of sample spot is lighter than the 400mg/dL spot, the level of IgG in the foal is less than 400mg/dL AKA FPT

3. if the sample spot color is the same as the 400mg/dL spot, partial passive transfer occurred

how to interpret the FPT SNAP test