The Kids Research Institute Australia
Publishes on Immune Cell Function and Interaction, Reproductive System and Pregnancy, IL-33, ST2, and ILC Pathways. 3 papers and 1.7k citations.
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The expression of Th2-skewed immunity against soluble protein Ags present in the normal environment is recognized as the primary cause of allergic inflammation in atopics. In contrast, nonallergic normal individuals display low level Th1-skewed immunity against the same Ags ("allergens"), which is perceived as conferring protection against Th2-dependent allergic sensitization. The type of T cell memory that develops against these Ags is currently believed to be the result of complex interactions between environmental and genetic susceptibility factors, which occur postnatally when the naive immune system directly confronts the outside environment. The results of the present study challenge this general concept. We demonstrate here for the first time that Th2-skewed responses to common environmental allergens, comprising IL-4, IL-5, IL-6, IL-9, and IL-13, are present in virtually all newborn infants and are dominated by high level production of IL-10. Moreover, these responses are demonstrable within 24 h of culture initiation, arguing against a significant contribution from covert in vitro T cell priming and/or differentiation. These findings imply that the key etiologic factor in atopic disease may not be the initial acquisition of allergen-specific Th2-skewed immunity per se, but instead may be the efficiency of immune deviation mechanisms, which in normal (nonatopic) individuals redirect these fetal immune responses toward the Th1 cytokine phenotype.
The neonatal T-cell system is capable of responding to allergens at birth, indicating the occurrence of prenatal sensitization, and the cytokine profile of these responses is skewed towards the Th-2 type. This response is further modified by postnatal exposure to different types of allergens. In relation to inhalant allergen (employed by HDM) the low level fetal Th-2 responses in non-atopics appear to be down-regulated rapidly after birth, parallel to an increase in allergen-specific IFN-gamma production. In contrast, atopics appear to consolidate their initial Th-2 responses, and around the age of 6 exhibit a cytokine response profile similar to the adult pattern. A pre-existing deficiency in IFN-gamma production may be one of the key factors determining the postnatal persistence of Th-2 responses in atopics.