Early Exposure to Respiratory Allergens by Placental Transfer and Breastfeeding

Abstract

The relationship between allergen exposure and the onset of or protection from allergic diseases remains unclear. Many factors could be related to immunological responses, such as the age when the exposure occurs, type of allergen, timing, dose, and allergen route. In this study, we investigated whether exposure to respiratory allergens could occur in pregnancy or early life. In particular, we assessed whether Der p 1 and Blo t 5, as well as specific antibodies against these allergens, could be detected in 90 paired cord blood and colostrum samples. Der p 1 was detected in 58.6% of colostrum and 29% of cord blood samples, whereas Blot 5 was positive in 41.3% and 9.6% of the samples, respectively. Similar to specific IgA, which could be detected in all samples for both mites, specific IgG was found in a high number of colostrum samples, 93.5% and 94.8% for Dp and Bt, respectively. Although allergens were not detected in all cord blood samples, a high percentage of them (≥95%) were positive for specific IgM to both mites in cord blood samples, suggesting that neonates can be exposed and sensitized to airborne allergens during pregnancy. Many studies have attempted to correlate allergen exposure or its prevention in early infancy with the onset of or protection from allergic diseases. However, conflicting and inconsistent data do not show a clear correlation with or suggest a way to prevent allergen sensitization. Nevertheless, these unconvincing results could be better understood if the relationship with many aspects of allergen exposure after pregnancy could be clarified. Thus, it is necessary to address basic issues related to allergen exposure, including the development of reproducible, standardized and reliable methods, and to determine how and where the exposure occurs.

Allergens of <b><i>Blomia tropicalis</i></b>: An Overview of Recombinant Molecules

“…Moreover, in the tropical and subtropical areas of the world, the importance of B. tropicalis as a cause of sensitization has been demonstrated [2,14,15,16,17] and even early life IgE responses to B. tropicalis have been reported [13,18]. Therefore, the advances in knowledge regarding the allergenicity of B. tropicalis and its profile of reactive allergens are imperative for the design of clinical interventions as well as the diagnosis of Blomia allergy.…”

A role for early oral exposure to house dust mite allergens through breast milk in IgE-mediated food allergy susceptibility

“…7 Studies in mice have examined conditions that are required to induce oral tolerance toward the food antigen ovalbumin (OVA) on its transfer through breast milk and showed that maternal milk factors such as TGF-b, vitamin A, and maternal OVA-specific IgG were required for oral tolerance induction and prevention of respiratory or food allergy. [8][9][10][11] Besides food allergens derived from the maternal diet, human milk is also a source of respiratory allergens such as Der p 1 and Blo t 5 from house dust mites (HDMs), 12,13 which are found in breast milk in the same range of concentration as dietary antigens such as OVA. 13 This observation is most probably related to the fact that most inhaled proteins are actually ingested because of respiratory tract mucociliary clearance [14][15][16] and will then follow the same route to the mammary gland as dietary antigens.…”

Maternal allergic asthma during pregnancy alters fetal lung and immune development in sheep: potential mechanisms for programming asthma and allergy

“…The complete placental barrier to antibody transport in sheep contrasts with humans, rats and mice, where antibodies are transferred across the placenta (Kane & Acquah, 2009). Allergens including Der p 1, the main allergenic component of HDM, also cross the human placenta (Macchiaverni et al 2015) and could therefore potentially contribute to development of fetal allergy. The available evidence suggests that increased progeny susceptibility to allergy is induced by a maternal inflammatory state, rather than fetal exposure to allergen/s or allergen-specific antibodies.…”