Neonatal Immunity


Both our innate and adaptive immune responses are reduced in function at birth. This leads to an increased risk of infection coinciding with a period of maximum exposure to new pathogens, caused by the move from the sterile environment of the womb to the infectious environment of the world. However, not every new antigen seen is dangerous to the newborn, and a balance is required to ensure an appropriate immune response and avoid inflammatory responses to benign antigens. To supplement the period of immune immaturity, the mother transfers passive protection, principally antibody, to the child. Vaccines can be used in early life, but the reduced function of the neonatal immune response reduces the efficacy of vaccines, which are otherwise effective in adults, necessitating research on infantā€specific formulations.

Key Concepts:

  • The neonate immune system is reduced in capacity and can be described as hyporesponsive.

  • The immune system develops in a programmed series of cell maturation events.

  • Moving from the controlled, sterile environment of the womb to the outside world has a critical impact on the newborn's immune system.

  • Reduced pattern recognition by neonatal antigenā€presenting cells leads to the observed hyporesponsive phenotype.

  • The mother provides some immune protection to the child, especially via antibodies in breast milk.

Keywords: newborn; fetus; breast milk; immune; maternal

Figure 1.

Downstream effects of reduced antigen‐presenting cell function in early life. Neonatal (APC) are exposed to a large number of previously unseen antigens. These antigens can either be benign and therefore should be tolerised or dangerous and therefore should induce an immune response. The neonatal APC have reduced recognition of antigens regardless of source (self, benign, pathogenic and vaccine). This is mediated at the level of (PRR) or the adaptor molecules that transduce them. This leads to reduced immune responses to these antigens and has an impact on vaccine efficacy, disease susceptibility and the development of asthma and allergy.



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Further Reading

Remington JS and Klein JO (eds) (2005) Infectious Diseases of the Foetus and Newborn Infant. Philadelphia: WB Saunders.

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How to Cite close
Tregoning, John S(Dec 2012) Neonatal Immunity. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0000956.pub3]