Cohort study of subclinical sensitization against galactose‐α‐1,3‐galactose in Japan: Prevalence and regional variations

Sensitization to galactose‐α‐1,3‐galactose (α‐Gal) leads to the development of α‐Gal syndrome, which includes red meat allergy and cetuximab‐induced anaphylaxis. Since tick bites represent the main cause of α‐Gal sensitization, it was speculated that sensitization to α‐Gal occurs throughout Japan. However, few cohort studies have investigated α‐Gal sensitization in Japan. Therefore, we aimed to elucidate the subclinical sensitization rate to α‐Gal in Japan. Sera were obtained from 300 participants without food or cetuximab allergy at Shimane University Hospital (Shimane prefecture), Tokyo Medical and Dental University Hospital (Tokyo metropolis), and Tohoku University Hospital (Miyagi prefecture). ImmunoCAP‐bovine thyroglobulin (BTG), ImmunoCAP‐beef, and IgE immunoblotting with cetuximab were performed to detect α‐Gal‐specific IgE. Clinical information was collected from participants using a questionnaire. The overall positivity rate of ImmunoCAP‐BTG was 4.0% without significant inter‐institute differences, whereas that for ImmunoCAP‐beef was 9.7% with a significant inter‐institute difference. Tokyo Medical and Dental University Hospital (19.0%) had the highest positivity rate. The positivity rate based on cetuximab IgE immunoblotting was 2.7%, without any significant inter‐institute differences. The overall positivity rate for both ImmunoCAP‐BTG and cetuximab immunoblotting was 2.0%, with a significant inter‐institute difference; 5.0% of Shimane University Hospital was the highest. Two cases showed sensitization against the non‐α‐Gal epitope of cetuximab. The overall positivity rate for both ImmunoCAP‐beef and cetuximab immunoblotting was 1.3%, without significant inter‐institute differences. Male sex was associated with positive beef‐specific IgE. The prevalence of subclinical sensitization to α‐Gal is estimated at 2.0%–4.0% in Japan and may be higher in rural areas, supporting an association between tick bites and α‐Gal sensitization. In contrast, the prevalence of subclinical sensitization to beef is 9.7% in Japan and is highest in Tokyo Metropolis, suggesting the presence of another IgE‐binding epitope apart from α‐Gal and another sensitization route in the sensitization to beef IgE.