Low‐level exposure to house dust mites stimulates T‐cell responses during early childhood independent of atopy

Abstract

The findings suggest that active immunological recognition of environmental allergens and the ensuing initiation of allergen-specific T-cell responses, is a normal part of the 'education' of the immune system in early childhood and can occur even at very low exposure levels. Priming per se does not imply clinically significant sensitivity, however.

Immune mechanisms of childhood asthma

“…148 In one study specific T cell reactivity to HDM was seen in the majority of two and three year old children; the lymphoproliferation results were similar in atopic and non-atopic children 149. Many adults have aeroallergen specific T cell reactivity demonstrable in vitro 148…”

Prenatal versus postnatal sensitization to environmental allergens in a high-risk birth cohort

“…25,26 However, the concept of fetal sensitization has been challenged, notably on the grounds of a lack of a quantitative relationship between maternal allergen exposure and T-cell responses in their newborn offspring. 27,28 Moreover, a recent expert review 29 has questioned the clinical evidence for a protective effect of maternal allergen avoidance. Despite this question, the COT recommendations have not changed, and it is unclear how these guidelines and the associated debate have impacted on the community at large.…”

The Developing Immune System and Allergy

“…246 Moreover, the use of sensitive microassays has detected the presence of low levels of allergen-specific (particularly food allergen) IgE antibodies in cord blood which are unrelated to maternal antibody profiles, arguing against cross-contamination, 29,30 though this has been disputed. 249,250 The T cell epitope map of the typical cord blood T cell response to ovalbumin (OVA), involving multiple regions of the OVA molecule, 251 suggests major qualitative differences relative to conventional adult T cell responses. 248 Alternatively, initial priming of T helper cells that drive production of these neonatal antibody responses may be against cross-reacting antigens as opposed to native allergen, and the uncertain relationship between maternal allergen exposure and newborn T cell reactivity is consistent with this view.…”