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. 2004 Feb;89(2):97–102. doi: 10.1136/adc.2002.013029

The early life origins of asthma and related allergic disorders

J Warner 1
PMCID: PMC1719801  PMID: 14736614

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Figure 1 .

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One of the explanations for maintenance of a successful pregnancy is that both Th-2 (IL-4 and IL-13) and T regulatory (IL-10 and TGF-ß) cytokines are generated by the conceptus to down-regulate maternal Th-1 immune responses to feto-paternal antigens which might otherwise lead to fetal rejection.

Figure 2 .

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The consequence of protection of the pregnancy by regulation of maternal Th-1/Th-2 balance is that the fetus is also exposed to a high concentration of Th-2 and T regulatory cytokines. These are present in the placenta, together with maternal IgE and allergens which have reached the amniotic fluid via the maternal circulation, leading to the potential for fetal allergic sensitisation, particularly as a consequence of swallowing and the generation of gut priming of the immune response. Antigen presenting cells, T cells, and B cells are mature within the fetal gut from as early as 16 weeks gestation.

Figure 3 .

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A number of factors counter-balance the drive to a fully committed Th-2 response to allergens in the fetus. These include the fetal generation of IFN-γ and a maternal supply of soluble CD14 which, in combination with endotoxin, will lead to stimulation of IL-12 and, therefore, IFN-γ production. Maternal lgG antibody which is actively transported across the placenta may block fetal allergan sensitisation.

Selected References

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