In vitro diagnosis of farmers' IgE-mediated allergy by Phadiatop® and three new multiallergen RAST analyses


Marianne van Hage-Hamsten, MD, Department of Clinical immunology, Karolinska Hospital, S-104 01 Stockholm, Sweden


Identification of persons with atopic allergy in a population is difficult if the pattern of sensitizing allergens is unique. Three new multiallergen tests, Professional Allergy Mixes (PAX) 1–3 (Pharmacia Diagnostics, Uppsala, Sweden), have recently been inttoduced to screen IgE-mediated allergy among farmers. PAX 1 contains animal danders and feathers, PAX 2 mites and insects, and PAX 3 pollens and molds. The value of these new tests for the determination of IgE-mediated allergy among fanners was compared with that of Phadiatop®, a test for general atopy. Of 440 farmers, 91 were positive to Phadiatop and 97 to any of PAX 1–3. None of the farmers were positive in all tests. Only 70/97 sera positive in RAST to PAX 1–3 had a positive Phadiatop, whereas of 91 sera positive in Phadiatop, 70 had specific IgE antibodies to PAX 1–3. The value of using either Phadiatop or PAX 1–3 is limited (sensitivity 74–79%), but, together, these four tests will detect almost all (95.9%) farmers with IgE-mediated sensitization and all (100%) with symptoms. We have also shown that the grain weevil Sitophilus grcmarius and the botfly Gaslerophihts intestinalis are important sources of allergens in rural environments.