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Imunology > Lecture 24 (Neonatal Immunity) > Flashcards

Lecture 24 (Neonatal Immunity) Flashcards

1
Q

why is a fetus considered a foreign antigen?

A

the sire has MHC molecules that are foreign and the dam is receiving those

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2
Q

what are the 4 maternal mechanisms for achieving maternal-fetal tolerance

A
  1. progesterone
  2. increased complement regulatory proteins
  3. TH2 response dominates (lower chance for TH1 mediated cytolysis of fetal tissues)
  4. high levels of Tregs
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3
Q

T-regulatory cells [heighten/dampen] your immune response

A

dampen

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4
Q

is a TH2 response humoral immunity or cell-mediated immunity?

A

humoral immunity

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5
Q

what are the 3 fetal mechanisms for achieving maternal-fetal tolerance

A
  1. fetal cells down regulate MHC I (lowers expression of self-antigens)
  2. TH2 cytokines are expressed
  3. inhibit T-cells (progesterone & other cytokines)
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6
Q

[MCH I/MHC II] is expressed on all nucleated cells

A

MHC I

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7
Q

t/f: the adult is less able to combat infections than a fetus

A

false - the fetus is less able to combat infections than an adult

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8
Q

reduced or absent adaptive immunity [decreases/increases] with fetal age

A

increases

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9
Q

despite early population of lymphoid tissues, the adaptive response is limited at birth…why?

A

there is limited antibody and T-cell diversity, no memory cells, and reduced cytokines (haven’t flushed out the system with exposure to antigens yet)

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10
Q

neonates have a slow and weak [innate/adaptive] response

A

adaptive

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11
Q

since the fetus has a reduced adaptive response, that means it relies on what three things?

A

-innate immunity
-passive immunity
-physical barriers

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12
Q

the adaptive immune response requires population of primary and secondary lymphoid organs in the ________ trimester

A

1st

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13
Q

when does the adaptive immune response start to increase in the fetus?

A

after population of lymphoid organs

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14
Q

due to reduced adaptive immunity, the fetus relies on what two things?

A

-its own innate immunity
-passive immunity from the dam

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15
Q

the fetal innate response and developing adaptive response can be passively supplemented by maternal _________

A

antibodies

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16
Q

placenta type where maternal epithelium is in contact with fetal tissues (fetal endothelium, CT, and epithelium)

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

a) epitheliochorial

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17
Q

placental type where there is no maternal epithelium, and instead the endothelium is in contact with fetal tissues (fetal endothelium, CT, and epithelium)

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

b) endothelialchorial

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18
Q

placental type where the fetal tissues (fetal endothelium, CT, epithelium) are in direct contact with maternal blood

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

c) hemochorial

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19
Q

what type of placenta do horses, swine, and ruminants have?

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

a) epitheliochorial

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20
Q

what type of placenta do dogs & cats have?

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

b) endothelialchorial

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21
Q

what type of placenta do humans, primates, and rodents have?

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

c) hemochorial

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22
Q

t/f: antibodies cannot pass through multiple layers of the placenta

A

true

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23
Q

any species that maintains all 6 of the placental layers are completely dependent on _____________ for transfer of their passive immunity

A

colostrum

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24
Q

what layers are lost in an epitheliochorial placenta?

A

none
*no maternal layers are lost

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25
Q

what layers are lost in an endotheliochorial placenta?

A

-maternal epithelial cells
-maternal connective tissue

26
Q

what layers are lost in a hemochorial placenta?

A

all three maternal layers:
-maternal epithelial cells
-maternal connective tissue
-maternal endothelial cells

27
Q

which placental type allows for complete transfer of colostrum?

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

c) hemochorial

28
Q

which placental type allows for partial transfer of colostrum?

a) epitheliochorial
b) endothelialchorial
c) hemochorial

A

b) endotheliochorial

29
Q

what percentage of total neonate serum IgG is transferred via the placenta in cats and dogs

A

~5-10%

30
Q

fetal humans, rabbits, and rodents have complete transfer of which immunoglobulin via the placenta?

A

IgG

31
Q

in addition to placental transfer, all species can receive maternal antibodies post-fetally via ______________

A

colostrum

32
Q

what is colostrum?

A

milk produced late in gestation and early postpartum that is high in antibody content

33
Q

the maximum amount of colostrum that can be absorbed is within the first ___ hours in foals and calves and then rapidly declines

A

6 hours

34
Q

which immunoglobulin is the only one to pass through the placenta?

A

IgG

35
Q

what explains why absorption of colostral Abs is time sensitive?

a) IgG is only produced by dams
b) IgG is known to degrade within 6 hours
c) FcR receptor expression falls off after 6 hours

A

c) FcR receptor expression falls off after 6 hours

36
Q

which immunoglobulin is predominant in ruminant milk?

A

IgG

37
Q

which immunoglobulin is predominant in non-ruminant milk?

A

IgA

38
Q

when is the maximum amount of colostrum absorbed from the neonatal intestine?

A

-first 6 hours in foals and calves
-within the first 12-24 hrs in other species

39
Q

t/f: colostrum has low lymphocyte count

A

false - has high lymphocyte count

40
Q

why is it important to consider the timing of when to vaccinate neonates?

A

-maternal antibodies can inhibit neonate Ig production (FcγRIIB)

-maternal antibodies can bind the vaccine antigen and block immune response (epitope masking, neutralization of live-attenuated viruses)

41
Q

when should you start vaccinating puppies and kittens?

A

6 wks of age then every 3 wks x3

42
Q

when should you start vaccinating foals and calves?

A

3-4 months of age then every 4 wks x3

43
Q

what are the negative aspects of passive immunity?

A

-maternal antibody may impair neonatal adaptive immune response

-FcγRIIB receptor engagement reduces BCR activation → masks antigens; may bind epitopes and prevent appropriate response to neonatal vaccines

-maternal antibodies may also recognize neonatal tissue (neonatal isoerythrolysis; Rh disease)

44
Q

what is neonatal isoerythrolysis?

A

when the mother has antibodies against the blood type of the newborn
*when the newborn ingests colostrum, it has antibodies against it’s own blood, causing destruction of RBCs

45
Q

what can you give to prevent neonatal isoerythrolysis?

A

artificial colostrum

46
Q

neonatal immunodeficiency can occur due to:

A

-can occur due to developmental failure
examples:
-innate response defects → trapped neutrophil syndrome (Border Collies)
-adaptive response → RAG-1/2 mutations
-can also occur due to failure of passive immunity transfer (vast majority)

47
Q

what is the most common source of immunodeficiency?

A

failure of passive immunity transfer (FPT)

48
Q

what is the major source of passive immunity?

A

maternal antibody transfer

49
Q

what are the 3 specific groups of causes of immunodeficiency?

A

-production failure → maternal (does not make antibodies)
-ingestion failure → placental or neonatal
-absorption failure → neonatal (major cause is lack of colostral transfer)

50
Q

discuss avian neonate immunity

A

-passive mechanisms of immunity transfer differ due to lack of placenta and lack of colostrum
-hen actively transfers IgY (=IgG) from serum to yolk → contents absorbed into bloodstream of developing chick
-IgM and IgA are secreted into the albumin in the oviduct (diffuse into amniotic fluid and swallowed by chick) → IgM and IgA in intestine (mucosal immunity)

50
Q

which of the following features promotes maternal-fetal tolerance?

a) high maternal levels of estrogen
b) high maternal complement expression
c) high maternal levels of progesterone
d) Th1 predominant immune response

A

c) high maternal levels of progesterone

51
Q

after maximum immunoglobulin consumption via colostrum, does the dam still provide immunity to the neonate?

A

yes, the dam continues to put immunoglobulin in colostrum (IgA) for mucosal immunity in the neonate

52
Q

in what species is failure of passive transfer most common?

A

horses

53
Q

list the 3 types of placenta

A

-epitheliochorial
-endotheliochorial
-hemochorial

54
Q

this receptor binds IgG at birth, protecting it from digestion and bringing it to circulation in neonate blood

A

fetal Fc receptor

55
Q

this receptor has high levels at birth and rapidly declines in number nearing 0 left by 24 hours

A

fetal Fc receptor

56
Q

t/f: you vaccinate an animal as maternal antibodies decrease and young animal’s adaptive immunity response begins to develop

A

true

57
Q

fescue hay having an endophyte that potentially causes a failure to produce colostrum is an example of which type of failure of passive immunity transfer?

A

production failure

58
Q

this type of FPT can be placental (abnormal placenta that precludes normal transfer) or neonatal (foal that won’t stand to nurse)

A

ingestion failure

59
Q

this type of FPT is mainly a cause of lack of colostral transfer such as taking in colostrum too late

A

absorption failure

60
Q

Hens actively transfer this antibody from serum to yolk that is equivalent to IgG

A

IgY

61
Q

_____ and ____ are two antibodies that are secreted into albumin in oviduct and diffuse into amniotic fluid and swallowed by the chick, ending up in the intestine

A

IgM and IgA

Imunology (10 decks)

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