Identification of galactose-α-1,3-galactose in the gastrointestinal tract of the tick Ixode sricinus; possible relationship with red meat allergy

Patients with IgE antibodies against the carbohydrate epitope galactose--1,3-galactose (-Gal) have reported severe allergic reactions after consumption of red meat. Investigations have revealed associations between IgE to -Gal and tick bites. We provide the first direct evidence that -Gal is present within ticks thus potentially explaining the relationship between tick exposure and sensitization to -Gal, with development of red meat allergy as a secondary phenomena. Serum from Swedish patients with delayed severe reactions to red meat was included in the study. A dose-dependent inhibition of IgE responses to -Gal by the tick Ixodesricinus is demonstrated. Furthermore, using cryostat-cut sections of I.ricinus, we show that both a monoclonal and a polyclonal antibody against -Gal stains the gastrointestinal tract of the tick. The same pattern is seen when staining with patient sera IgE positive to -Gal. These results confirm that the -Gal epitope is present in I.ricinus and imply host exposure to -Gal during a tick bite. This provides further evidence that tick bites are associated with IgE responses to -Gal and red meat allergy.