Ascaris-specific IgE and allergic sensitization in a cohort of school children in the former East Germany

Background: Helminthic infections induce an IL-4-dependent polyclonal stimulation of IgE synthetization. It is still unclear, however, what role helminths play in allergic sensitization. Objective: We sought to determine the relationship between Ascaris-specific IgE and allergic sensitization in a nontropical country. Methods: In 2 consecutive cross-sectional surveys in 1992-1993 and 1995-1996, data from school entrants (age range, 5 to 7 years), third graders (age range, 8 to 10 years), and sixth graders (age range, 11 to 14 years) were collected. The 2 younger groups were reexamined in the second survey. Data for about 2300 children, including a cohort of 700 subjects, were analyzed. Ascaris IgE and total and specific IgE to inhalant allergens were measured, and skin prick tests were performed, Information about asthma and allergic rhinitis was collected by a questionnaire. Results: Children who were Ascaris-IgE seropositive (>0.35 IU/mL) in both surveys had 10-fold higher levels of total IgE (451 IU/mL vs 45 IU/mL, P <.001) and higher prevalence rates of allergen-specific IgE seropositivity (56.3% vs 26.6%, P <.001). They also had a higher prevalence of allergic rhinitis (12.6% vs 3.7%, P <.001) and asthma (5.7% vs 1.6%, P <.05). In subjects who were Ascaris-seronegative in the first survey but seropositive in the second survey, total and specific IgE increased markedly. Sensitization to Dermatophagoides pteronyssinus increased nearly 3-fold in this group. In contrast, in children who became Ascaris-seronegative, total and specific IgE decreased. Conclusions: Contact with low doses of helminthic antigen is associated with an increase of total and specific IgE production. Helminthic infections in East German children are not the cause for a low prevalence of allergies in the former East Germany.