Neonatal Immunity
Ig's
IgG - Active transport
ratio baby:Mom
Term - 1
32 wk - 0.5
28 wk - 0.3
> 1500gm -> hypoammaglobuinemic 200 - 300 mg/dl in first wk of life.
Ø E. Coli protection
Complement:
Ø transfer
Baby produces from 1° trimester
@ birth
Slightly diminished classsic pathway activity
Moderately diminished alternate pathway activity - components (B & P) =
35-60%
Premature infants have lower levels of compliment components & activity
- Normal opsonization of Staph but variable with GBS & E. Coli.
Neutrophils
Diminished Chemotaxis
Dec - Adherence, aggregation & deformability - which delays response to
infection.
- in healthy newborns with adequate opsonization, phagocytosis and killing of
neutrophils is comparable to adults
- but decreased in:
RDS
Hypoglycemca
hyperbilli
sepsis
# of circulating neutrophils is inc after birth - Peaks @ 12 hrs & normal @ 22 hrs.
Bands are < 15% in normal newborns & may inc in newborns with infecton &
stress such as asphyxia.
immature:total ratio of 0.16 or greater is suggestive of bact infection
Monos-Macrophage
# of monos are normal
mass & function of macrophages in the RES is dec in newborns esp premature
Cytokines
INF - æ & ß normal
INF - ¥ are inc in infants with sepsis
IL-2 activity is increased
IL-6 inc in serum with sepsis & NEC
Abx Rx
- infetion
7 - 10 days or 5 - 7 days after clinical response
- Meningitis (GBS)
14 days
- repeat cx in 24 - 48 hrs
dn
Neonatal Immunity
1
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