Allergy to goat and sheep cheese with good tolerance to cow cheese

Background We report on a patient who experienced allergic reactions after eating goat cheese and after touching goat and sheep cheese, but not after consuming cow's milk dairy products. Objective To assess the allergenicity and IgE-binding capacity of the casei ns from the three different species. Methods Skin prick tests were carried out using whole milk and caseins from three different species (goat, sheep and cow), and whey fractions of cow's milk. Total serum IgE and specific IgE to cow's milk proteins were measure d by CAP system and specific IgE against caseins and whole milk were determ ined by ELISA technique. To evaluate allergenic cross-reactivity, inhibitio n of the IgE ELISA activity to goat's milk and goat casein was tested for t he three caseins. SDS-PAGE and immunoblotting was used to determine IgE bin ding bands in caseins. Results Skin tests were positive to sheep and goat's milk, sheep and goat c asein, as well as to sheep and goat cheese. Total serum IgE was 66 kU/L and IgE determinations by CAP were negative. IgE ELISA against the caseins fro m goat and sheep was strongly positive, whereas it was negative to cow case in. ELISA inhibition assays revealed a high degree of cross-reactivity betw een goat casein and sheep casein. Immunoblotting showed three IgE-binding b ands in goat casein at 31, 27 and 22 kDa, which may correspond to alpha-, b eta- and gamma-caseins. A band at about 31 kDa was observed in sheep casein and another band at 34 kDa was recognized in cow casein. Conclusion This patient developed allergy to goat and sheep cheese with goo d tolerance to cow's milk. We identified goat casein as the main allergen c ausing sensitization in this patient as demonstrated by in vivo and in vitr o tests. A high degree of cross-reactivity between goat and sheep casein wa s observed.