[Different threshold concentrations for sensitization by cattle hair allergen Bos d 2 in atopic and non-atopic...

Several threshold values for indoor allergens leading to IgE sensitization were proposed. Currently such values exists for allergens of house dust mite, cat, dog, and cockroach and cattle. A high sensitization is known as an important risk factor in the development of asthma. This study was undertaken to examine threshold values of major cow hair allergen Bos d 2 in the house dust of atopic and nonatopic cow hair asthmatic farmers. 45 patients with cow hair asthma were visited at their homes. House dust samples were taken from corridor, living room, and bedroom. The concentration of Bos d 2 was determined by means of rocket immunoelectrophoresis. Additionally, samples of venous blood were taken to demonstrate specific IgE towards cow epithelia by CAP-RAST. Five patients were excluded from further investigations because they have given up their cattle for less than 6 months. In 21 patients occurred typical atopic stigmata like infantil history of atopic eczema, hay fever or milk crust, while the other 19 subjects did not show an atopic diathesis. High sensitization towards cow epithelia (specific IgE > 0.7 kU/l in CAP-RAST) occurred significantly more often in atopics than in nonatopics. In atopic subjects the allergen concentrations leading to IgE sensitization amounted to 1-20 micrograms Bos d 2/g dust, whereas in nonatopics were found higher Bos d 2 threshold values (25-50 micrograms/g dust). The present study suggests that in nonatopic cow hair asthmatics high indoor Bos d 2 levels lead to IgE sensitization as well as the close contact to cattle.