Extract and molecular-based early infant sensitization and associated factors-A PreventADALL study.

Background: More knowledge about sensitization patterns in early infancy, including impact of molecular allergology, is needed to help predict future allergy development more accurately.

Objective: We aimed to determine the prevalence and patterns of allergic sensitization at 3 months of age, and explore possible associated factors.

Methods: From the Scandinavian antenatally recruited PreventADALL mother-child cohort, we included 1110 3-month infants with available serum. Sensitization was defined as s-IgE of ≥0.1 kU /L by Phadiatop Infant (ThermoFisher Scientific) including birch, cat, grass, dog, milk, egg, peanut and wheat. Further ImmunoCAP analyses to ovomucoid, casein, Ara h 1-3, omega-5-gliadin were performed in food extract s-IgE-positive children. Maternal sensitization was defined as s-IgE ≥ 0.35 kU /L to Phadiatop (inhalant allergen mix) and/or Fx5 (food allergen mix) at 18-week pregnancy.

Results: Overall 79 (7.3%) infants had specific sensitization, many with low s-IgE-levels (IQR 0.16-0.81 kU /L), with 78 being sensitized to food extract allergens; 41 to egg, 27 to milk, 10 to peanut, and 25 to wheat. A total of 62/78 were further analysed, 18 (29%) had s-IgE to ovomucoid, casein, Ara h 1-3 and/or omega-5-gliadin. Eight infants (0.7%) were sensitized to inhalant allergens. Maternal sensitization to food allergens was associated with infant sensitization, odds ratio 3.64 (95% CI 1.53-8.68).

Conclusion: Already at 3 months of age, 7% were sensitized to food, mostly without detectable s-IgE to food allergen molecules, and <1% to inhalant allergens. Maternal food sensitization was associated with infants' sensitization.