Differences in the sensitisation to ragweed pollen and occurrence of late summer allergic symptoms between native and immigrant workers of the nuclear power plant of Hungary.

Regular medical screening including allergic symptoms of workers of the Nuclear Power Plant in Paks, Hungary, offered a unique opportunity to study the influence of the environmental factors on the development of allergy. The city Paks has been one the areas of the country most heavily exposed to ragweed pollen allergens. The occurrence and extent of sensitisation assessed by skin prick test to common allergens and prevalence of seasonal and perennial allergic symptoms were compared among 880 workers (695 immigrants, 185 natives) with self-reported allergic symptoms. The percentage of sensitised people against common allergens (ragweed, grass, D. pteronyssinus) was almost the same in the natives and immigrants. When, however, the strength of sensitivity to ragweed was determined by quantitative skin prick test and specific IgE determination, significantly (P<0.0001) more immigrants (69%) than native workers (20%) exhibited high sensitivity to ragweed and the titres of specific IgE antibodies was also significantly (p < 0.0001) higher in the former group. Similar differences were found in the occurrence and type of allergic symptoms. Seasonal symptoms alone occurred in 69% and 38% of the immigrant and native workers (p < 0.0001). This difference was mostly due to those with late summer symptoms characteristic to ragweed allergy. These symptoms occurred in 57% of the immigrant workers, much more frequently (p < 0.0001) than in the natives (18%). Our findings indicate that the length of exposure to an inhalant allergen does affect the extent of sensitisation to ragweed allergen and markedly influences the clinical symptoms that develop in the ragweed allergic patients upon allergen exposure. It can be assumed that the natives who have been living with ragweed pollen for a long time (that is were exposed to natural immunotherapy), developed a natural tolerance to it.