Humoral Immune Responses to Pig Urinary Proteins and Respiratory Health of Pig Farmers

ABSTRACT Pig stable dust may contain large amounts of potentially allergenic pig urinary proteins (PUP). In this study, inhibition enzyme immunoassays were used to measure airborne PUP expo-sure, and high levels (up to 200 μgeq/m3) could indeed be demon-strated in personal inhalable dust samples of pig farmers. IgE and IgG4 anti-PUP were assessed in the sera of 191 pig farmers, for whom also questionnaire and bronchoprovocation data were avail-able. IgE anti-PUP was found in only 5-7%, and was at best weakly associated with respiratory symptoms. In contrast, IgG4 anti-PUP was found in many subjects, and titres were negatively associated with respiratory health problems, and also with bronchial hyperreac-tivity to histamine. Anti-PUP IgG4 antibodies thus seem to protect pig farmers from developing respiratory symptoms and BHR.