Increase of allergen‐specific immunoglobulin E antibodies from 1973 to 1994 in a Finnish population and a possible relationship to Helicobacter pylori infections1

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Abstract
Background The prevalence of atopic diseases – hayfever, asthma and eczema – has increased over the past decades. The increase may be associated with decreased rates of infections such as measles, hepatitis A, tuberculosis, toxoplasmosis, and, as recently suggested, Helicobacter pylori gastritis. Objective Since the increase of atopy has been mainly based on clinical studies, we wanted to study the prevalence of allergen‐specific Immunoglobulin (Ig)E antibodies in two cross‐sectional, adult population‐based serum samples two decades apart. Since the sera had been tested for H. pylori antibodies, we also had a chance to look for a possible relationship between these two findings. Methods We determined the prevalence rate of allergen‐specific serum IgE antibodies against birch and timothy pollen, and cat and dog epithelium allergens by the radioallergosorbent test in a 15–54‐years‐old Finnish population using 326 sera collected in 1973 and 319 sera collected in 1994 from randomly selected subjects. Results From 1973 to 1994 allergen‐specific IgE prevalence rates and IgE antibody levels rose. In 1994, the prevalence rate of positive findings in 15–24‐year‐old population had increased from 11 to 38% (3.5‐fold increase, P = 0.0001, OR 5.12, CI 95% 2.32–11.3). In older 10‐year age groups similar trends did not reach significance, but the overall change was significant with all three cut‐off levels of allergen‐specific IgE analysed. The percentage of IgE‐positive persons rose mainly in the subgroup with no H. pylori antibodies. In 1994 21% of the H. pylori‐negative subjects had IgE antibodies compared with 5% of the H. pylori‐positive subjects (in 1973 11% in both subgroups). Conclusions IgE‐based evidence for an increase in IgE‐mediated allergy was uncovered. The increase occurred mainly in the subgroup with no antibodies to H. pylori, which support the hypothesis that H. pylori could be one of the microbes counteracting atopy.