Neonatal Immunity Introduction
Neonates start life with immature immune systems. They rely on maternal antibodies transferred in utero via the placenta and postnatal through breast milk, providing passive immunity during early development.
Passive Immunity Components
Passive immunity is mediated by IgG antibodies crossing the placenta and IgA in colostrum. This protects newborns against pathogens from their immediate environment until their own immune system matures.
Active Immunity Development
Neonates gradually develop active immunity. Initially, they exhibit a Th2-biased response, favoring antibody production over cell-mediated immunity, which evolves into a balanced Th1/Th2 response with antigen exposure.
Neonatal Immune Challenges
The neonatal period is critical for immune system programming. Exposure to diverse pathogens, vaccinations, and environmental factors can significantly influence the immune system's development and long-term function.
Unique Neonatal Leukocytes
Neonatal leukocytes differ from adults'; they show reduced phagocytic activity, lower cytokine production, and diminished antigen-presenting capabilities, which contributes to their unique immune responses.
Microbiome's Immune Role
The establishment of the neonatal microbiome is crucial for immune system maturation. Gut colonization by bacteria stimulates immune development, teaching the body to distinguish between harmful and beneficial organisms.
Vaccination Impact
Vaccinations are pivotal for newborns, offering protection as their immune system matures. They stimulate the neonate's immune system to produce its own antibodies and memory cells, providing lasting immunity.
What immunity do neonates initially rely on?
Active immunity from birth
Maternal passive immunity transfer
Vaccination-induced immunity
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