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Prenatal contact with inhalant allergens
K Van Duren-Schmidt1, J Pichler, C Ebner
1Department of Pediatrics, University of Vienna, Austria.
Insights
Maternal inhalation of pollen allergens during pregnancy can lead to prenatal immune system priming. The fetal immune system can be primed, particularly in early pregnancy, suggesting T cells mature early.
Area of Science:
- Immunology
- Allergy Research
- Maternal-Fetal Medicine
Background:
- Early childhood pollen exposure is linked to increased allergy risk.
- Prenatal exposure to allergens via maternal inhalation is a potential factor in immune sensitization.
- Understanding fetal immune system maturation is crucial for allergy prevention strategies.
Purpose of the Study:
- To investigate the likelihood of prenatal contact with pollen allergens through maternal inhalation.
- To assess the maturation of the fetal immune system by analyzing responses to specific allergens.
- To determine if prenatal allergen exposure influences the risk of developing pollen allergies.
Main Methods:
- Analysis of proliferative responses in umbilical cord blood mononuclear cells (UCB MNCs).
- Testing UCB MNCs against recombinant major allergens of birch (rBet v 1) and timothy grass (rPhl p 1) year-round.
- Correlating positive proliferative responses with estimated dates of prenatal allergen exposure.
Main Results:
- Prenatal immune priming was observed for both birch and timothy grass allergens.
- Timothy grass pollen showed significantly higher antigenicity compared to birch pollen.
- The fetal immune system's susceptibility to priming varied during gestation, with most responses occurring when maternal exposure happened in the first 24 weeks of pregnancy.
Conclusions:
- Indirect evidence suggests T cells are mature enough for antigen priming shortly after migrating to the thymus.
- Prenatal exposure to pollen allergens can occur and prime the fetal immune system.
- No correlation was found between fetal immune priming susceptibility and family history of type I allergy.
Abstract:
Pollen contact in early infancy may enhance the risk for subsequent pollen allergy. In this study likelihood of a prenatal antigen contact, as a result of inhalation of pollen allergens by the mother, was investigated. Due to the seasonal occurrence of allergens studied, the date of priming can be estimated, and this can supply data about the maturation of the fetal immune system. Proliferative responses of umbilical cord blood mononuclear cells (UCB MNCs) to the recombinant major allergens of birch (rBet v 1) and timothy grass (rPhl p 1) were analyzed throughout the whole year. A positive proliferative response was regarded as the criterion for a prenatal contact of the immune system with the allergen. Prenatal priming with both allergens was observed. Timothy grass pollen displayed considerably higher antigenicity than did birch pollen. The susceptibility of the fetal immune system to be primed by these allergens varies during the gestation period. The majority of positive responses to rPhl p 1 and rBet v 1 were found in UCB samples in which antigen contact (the respective pollen season) took place in the first 6 mo of pregnancy. Our results offer indirect evidence that, shortly after migration of T cell precursors to the epithelial thymus, T cells are mature enough for priming with antigens. No relationship was found between the susceptibility of the fetal immune system to be primed by these allergens and the clinical history of the family concerning type I allergy.