Immune responses to birch during the first seven pollen seasons of life

Background: Exposure to allergens early in life may have an impact on the i ncidence of allergy many years later, but the kinetics of the immune respon ses have still not been studied prospectively. Therefore, we wanted to stud y the development of immune responses of the Th1 and Th2 type to birch over the first pollen seasons. Material and Methods: Blood samples were obtaine d from 21 prospectively followed children during the second to the seventh pollen season of life. IgG subclass antibodies to rBet v1 were analyzed by ELISA, IgE antibodies to birch with Magic Lite (TM) and birch-induced monon uclear cell proliferation by H-3-thymidine incorporation. Results: Prolifer ative responses and IgG1 antibodies were commonly seen both in children wit h and without allergic symptoms and sensitization to birch. Most nonsensiti zed children had a transient lgG4 antibody response, which was downregulate d after the third pollen season, while the titers of this Th2-associated su bclass increased with age in sensitized children with clinical symptoms to birch. Conclusions: Immune responses to birch can be demonstrated in childr en regardless of atopic status. A transient early Th2-like response is down regulated after the third pollen season in nonatopic but not atopic childre n. Copyright (C) 2001 S.Karger AG,Basel.