Supplementary Material for: Early Life Interventions to Prevent Allergy in the Offspring: The Role of Maternal Immunization and Postnatal Mucosal Allergen Exposure

<i>Background:</i> Childhood allergy is influenced by maternal factors and allergen exposure in early life, but the factors that determine the development of allergy and tolerance are unknown. Therefore, we compared the effects of two early life interventions, i.e. maternal allergen immunization and postnatal intranasal allergen exposure, as well as a combination of both treatments on allergic responses in the offspring. <i>Methods:</i> Female mice were immunized with ovalbumin (OVA) or vehicle during pregnancy. After birth, half the offspring from each group were exposed intranasally to low doses of OVA or vehicle weekly for 5 weeks before intraperitoneal immunization with OVA. <i>Results:</i> Maternal immunization reduced OVA-specific IgE and IgG1, but increased IgG2a and T<sub>H</sub>2 cytokine responses in the offspring after immunization. Postnatal intranasal OVA exposure similarly reduced both IgE and IgG1, but also spleen cell numbers and cytokine secretion. Following airway challenges of the offspring, IgE and airway inflammation were suppressed only by intranasal exposure, but not by maternal immunization, the effect of which also waned with age. Differential gene expression in the spleen of offspring supported that IgE suppression by the two interventions was caused by different mechanisms. Despite this, tolerance development after mucosal exposure was obtained in the offspring of immunized dams. <i>Conclusions:</i> The study suggests that prevention of allergy is possible if initiated in early life, and early mucosal allergen exposure may play a protective role independent of the maternal immune responses.