Trajectories of IgE, IgA and IgG Levels in Preschool-Aged Children: Insights From the Subcohort Study of the Japan Environment and Children's Study.

Background: There is a significant lack of longitudinal research on specific immunoglobulin E (IgE), IgA, and IgG sensitisation levels among preschool-aged children, despite their critical role in elucidating the mechanisms underlying allergic disorders. The current study analysed the trajectories of IgE, IgA, IgG1, and IgG4 levels across general populations and their correlation with allergic diseases in children aged 2-4 years.

Methods: This longitudinal study included 4872 children aged 2 years and 4437 children aged 4 years who participated in the Subcohort Study of the Japan Environment and Children's Study. Allergic diseases were evaluated utilising the diagnostic criteria established by the International Study of Asthma and Allergies in Childhood and the UK Working Party. The serum specific IgE (sIgE), IgG1, IgG4, and IgA levels of participants aged 2-4 years were quantified.

Results: The prevalence of atopic dermatitis, hen's egg allergy, cow's milk allergy, and current wheezing decreased between ages 2 and 4 years. The prevalence of allergic rhinitis and conjunctivitis exhibited an upward trend. The serum IgE levels to hen's egg and cow's milk antigens in healthy children were similar to those in children with allergic diseases, and it decreased between ages 2 and 4 years. Der p1 sIgE levels decreased in healthy children, whereas they increased in allergic children. The high sIgE/total IgE and sIgE/specific IgG4 levels to Derf1 and Derp1 at age 2 years were associated with current wheezing at age 4 years.

Conclusions: This study provided foundational benchmark values for IgE, IgG1, IgG4, and IgA levels against different allergens in a general population of children aged < 5 years. The levels of each allergen exhibited distinct characteristics in the general population.