Extract and molecular-based early infant sensitisation and associated factors - a PreventADALL study.

BACKGROUND: More knowledge about sensitisation 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 sensitisation at three months of age, and explore possible associated factors.

METHODS: From the Scandinavian antenatally recruited PreventADALL mother-child cohort we included 1110 three-months-infants with available serum. Sensitisation was defined as s-IgE of ≥0.1 kUA /l by Phadiatop Infant® (ThermoFisher Scientific, Sweden) 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 sensitisation was defined as s-IgE ≥0.35 kUA /l to Phadiatop® (inhalant allergen mix) and/or Fx5 (food allergen mix) at 18-week pregnancy.

RESULTS: Overall 79 (7.3%) infants had specific sensitisation, many with low s-IgE-levels (IQR 0.16-0.81 kUA /l), with 78 being sensitised to food extract allergens; 41 to egg, 27 to milk, 10 to peanut, and 25 to wheat. 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 sensitised to inhalant allergens. Maternal sensitisation to food allergens was associated with infant sensitisation, odds ratio 3.64 (95% CI 1.53-8.68).

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