Neonatal Immunity

Abstract

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 antigen‐presenting cells (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 pattern recognition receptors (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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References

Adkins B, LeClerc C and Marshall‐Clarke S (2004) Neonatal adaptive immunity comes of age. Nature Reviews Immunology 4(7): 553–564.

Billingham RE, Brent L and Medawar PB (1953) Actively acquired tolerance of foreign cells. Nature 172(4379): 603–606.

Blom B and Spits H (2006) Development of human lymphoid cells. Annual Review of Immunology 24: 287–320.

Costello EK, Stagaman K, Dethlefsen L, Bohannan BJ and Relman DA (2012) The application of ecological theory toward an understanding of the human microbiome. Science 336(6086): 1255–1262.

Englund JA (2007) The influence of maternal immunization on infant immune responses. Journal of Comparative Pathology 137(Suppl. 1): S16–S19.

Fox KA and Theiler R (2011) Vaccination in pregnancy. Current Pharmaceutical Biotechnology 12(5): 789–796.

Gibbons DL, Haque SF, Silberzahn T et al. (2009) Neonates harbour highly active gammadelta T cells with selective impairments in preterm infants. European Journal of Immunology 39(7): 1794–1806.

Goriely S, Vincart B, Stordeur P et al. (2001) Deficient IL‐12(p35) gene expression by dendritic cells derived from neonatal monocytes. Journal of Immunology 166(3): 2141–2146.

Hodgins DC and Shewen PE (2012) Vaccination of neonates: problem and issues. Vaccine 30(9): 1541–1559.

Kim D and Niewiesk S (2011) Sidestepping maternal antibody: a lesson from measles virus vaccination. Expert Review of Clinical Immunology 7(5): 557–559.

Klein KP and Bont L (2008) Neonatal and infantile immune responses to encapsulated bacteria and conjugate vaccines. Clinical and Developmental Immunology 2008: 628963.

Levy O (2007) Innate immunity of the newborn: basic mechanisms and clinical correlates. Nature Reviews Immunology 7(5): 379–390.

Macpherson AJ, McCoy KD, Johansen FE and Brandtzaeg P (2008) The immune geography of IgA induction and function. Mucosal Immunology 1(1): 11–22.

Olszak T, An D, Zeissig S et al. (2012) Microbial exposure during early life has persistent effects on natural killer T cell function. Science 336(6080): 489–493.

Pihlgren M, Tougne C, Bozzotti P et al. (2003) Unresponsiveness to lymphoid‐mediated signals at the neonatal follicular dendritic cell precursor level contributes to delayed germinal center induction and limitations of neonatal antibody responses to T‐dependent antigens. Journal of Immunology 170(6): 2824–2832.

Siegrist CA and Aspinall R (2009) B‐cell responses to vaccination at the extremes of age. Nature Reviews Immunology 9(3): 185–194.

Velilla PA, Rugeles MT and Chougnet CA (2006) Defective antigen‐presenting cell function in human neonates. Clinical Immunology 121(3): 251–259.

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. http://www.els.net [doi: 10.1002/9780470015902.a0000956.pub3]