O11.1 ENDOTOXIN EXPOSURE AND ATOPIC SENSITIZATION IN ADULT PIG FARMERS

D. Heederik¹, L. Portengen¹, L. Preller², G. Doekes¹.¹Institute for Risk Assessment Sciences (IRAS), University of Utrecht, The Netherlands; ²Department of Chemical Exposure Assessment, TNO Chemistry, The Netherlands

Introduction: Recent studies have reported a considerable lower prevalence of atopic sensitization and symptoms of respiratory allergy in children growing up on farms compared with their peers living in the same rural areas. We therefore wanted to evaluate whether adult farmers also have a reduced risk for atopic sensitization and whether such a possible reduced risk is associated with endotoxin exposure.

Methods: Complete data on endotoxin exposure, total serum IgE, and presence of IgE to house dust mite, grass pollen, birch pollen, and cat dander were available for 162 pig farmers from a cross sectional case–control study. Exposure to endotoxin was measured on more than one occasion and modelled in detail. Exploratory analysis was performed using non-parametric modelling and was followed by classical multiple logistic regression.

Results: IgE to one or more common allergens was detected in sera from 28 pig farmers (17%) and average (geometric mean (geometric SD)) total serum IgE was 37 (4) IU/mL. A strong inverse relation was found between endotoxin exposure and sensitization to common allergens for exposures up to 75 ng/m³, with an OR (95% confidence interval (CI)) of 0.3 (0.1 to 0.9) for >75 versus ⩽75 ng/m³ endotoxin. No association was found between endotoxin and total serum IgE.

Conclusions: The prevalence of atopic sensitization to common allergens in adult pig farmers is low. Exposure to endotoxin or related exposures appear to protect from sensitization to common allergens in an adult working population exposed to high levels of endotoxin.

O11.2 PROGRESSION OF SYMPTOMS IN LABORATORY ANIMAL ALLERGY

L. Elliott¹, D. Heederik², D. Loomis¹.¹Department of …