Haemaphysalis longicornis tick bites are a possible cause of red meat allergy in Japan

Recent studies revealed that Amblyomma or Ixodes tick bites may cause red meat allergy, in which galactose-α-1,3-galactose (α-Gal) is a major IgE-binding epitope. The incidence of red meat allergy is high in Shimane Prefecture, as is tick-transmitted Japanese spotted fever. Therefore, we speculated that tick bites may cause these meat allergies. The carbohydrate α-Gal was detected in the salivary gland protein of Haemaphysalis longicornis (H. longicornis), the vector for Japanese spotted fever, by immunoblotting using anti-α-Gal antibody. H. longicornis salivary gland protein-specific IgE was detected in the sera of 24 of 30 patients with red meat allergies. Sensitization to tick salivary gland protein containing α-Gal is possibly a major etiology of red meat allergy; the carbohydrate plays a crucial role in its allergenicity. These results further indicate that the α-Gal epitope is present not only in Amblyomma or Ixodes, but also in Haemaphysalis.

Laminin γ-1 and collagen α-1 (VI) chain are galactose-α-1,3-galactose-bound allergens in beef

BACKGROUND

Sensitization to the carbohydrate galactose-α-1,3-galactose (α-Gal) has been reported in patients with beef allergy. However, the proteins responsible for this allergy have not yet been identified. This study aimed to identify beef proteins that predominantly react with serum IgE in Japanese patients with beef allergy.

METHODS

Sera were collected from 29 patients with beef allergy who had allergic reaction(s) such as urticaria, abdominal pain, vomiting, and anaphylactic shock after ingestion of beef and pork; the sera tested positive for IgE against beef and pork. IgE-binding proteins were detected by immunoblotting sera from the patients and identified using a combination of two-dimensional gel electrophoresis and peptide mass fingerprinting techniques. The involvement of carbohydrate in the binding of IgE to allergens was examined by periodate treatment and an inhibition assay with cetuximab by immunoblotting. Specific IgE binding to cetuximab was measured using the CAP-fluorescent enzyme immunoassay.

RESULTS

Two IgE-binding proteins (240 kDa and 140 kDa) were detected in beef extract and identified as laminin γ-1 and the collagen α-1 (VI) chain from Bos taurus, respectively. Periodate treatment or the inhibition assay resulted in the loss of IgE binding to these proteins. Immunoblotting with anti-α-Gal antibody revealed the presence of α-Gal on the 240- and 140-kDa beef proteins. The amount of IgE bound to cetuximab was significantly correlated with that to beef in the patients with beef allergy.

CONCLUSION

The carbohydrate moiety (α-Gal) on laminin γ-1 and collagen α-1 (VI) chain are possibly common IgE-reactive proteins in the Japanese patients with beef allergy.