Longitudinal Changes of Sensitization to Farming-Related Antigens among Young Farmers

Abstract

Background: We have shown previously that the prevalence of allergic sensitization in Tyrolean farming students is high, with a clear relationship to occupational exposure. Objectives: It was the aim of this investigation to assess longitudinal changes in sensitization and a possible impact on lung function. Methods: Of the 147 farming students in the original cohort, we could re-examine 42 after a mean interval of 4.0 years. All individuals completed a questionnaire and had spirometry, skin prick tests, total and specific IgE analysis, and testing for precipitating antibodies. Results: As compared to the first study, there was a decrease in the frequency of IgE-mediated allergy (30.1 vs. 54.8%; p < 0.05) and in total serum IgE levels (107.4 ± 254 vs. 157.8 ± 304 U/ml; p < 0.001). Conversely, 3 individuals had developed precipitating antibodies de novo, and those who had initially had a positive precipitin test (n = 6) were still positive. A larger-sized estate, the lack of a hay dryer, and the presence of moldy hay were confirmed as risk factors for allergic sensitization. Although there was a slight overall decrease in forced vital capacity, no new cases of occupational lung disease were found. Conclusions: In young Tyrolean dairy farmers, the prevalence of precipitins is constantly high and rising while IgE-mediated allergy declines. Within 4 years, no clinically relevant impact of allergy on lung function was noticed.

Exposure–response analysis of allergy and respiratory symptoms in endotoxin-exposed adults

“…Conversely, endotoxin is thought to reduce the risk of allergic sensitisation by inducing a shift from allergic T-helper cell (Th) type 2 responses to Th1-dominated responses, through stimulation of the innate immune system and regulatory T-cells [28]. The results of the present study suggest that inhaled endotoxin may exert such immune-modulating effects beyond childhood, and similar conclusions were previously derived from a longitudinal study showing that young adult dairy farmers may lose allergic sensitisation over time, especially to grass pollen [29].…”

The Two Sides of the “Endotoxin Coin”

“…52 Although it is assumed that it is the early-life farm contact that confers a protective effect against allergic diseases, new data show that regular farm animal contact starting later in life is also associated with a decreased prevalence of sensitisation among adults. 53 Two small longitudinal studies among young adults 54 and schoolchildren 55 suggest that farm animal contact starting at a later age not only reduces the incidence, but is also associated with a more frequent loss of sensitisation. The study among 42 Austrian agricultural students 54 showed a remission of allergic disease among those with new contact to farm animals; the study, however, was hampered by a high loss to follow up.…”

“…53 Two small longitudinal studies among young adults 54 and schoolchildren 55 suggest that farm animal contact starting at a later age not only reduces the incidence, but is also associated with a more frequent loss of sensitisation. The study among 42 Austrian agricultural students 54 showed a remission of allergic disease among those with new contact to farm animals; the study, however, was hampered by a high loss to follow up. The other study 55 was a three year follow up of 844 Austrian schoolchildren (mean age at baseline 8 years).…”

The effect of occupational farming on lung function development in young adults: a 15-year follow-up study

“…Prior et al 9 showed a slight overall decrease in FVC over a 4-year follow-up period in a group of 42 young farmers. A larger population-based study showed that after 9 years of follow-up, young individuals exposed to dusts, gases and fumes in different occupations (including farming) did not have a steeper overall decline in lung function than individuals without occupational exposure 10.…”