• Hideo Hashizume, Toshiharu Fujiyama, Takatsune Umayahara, Reiko Kageyama, Andrew F Walls, and Takahiro Satoh.
• Department of Dermatology, Shimada Municipal Hospital, Shimada, Japan. Electronic address: hihashiz0001@mac.com.
• J. Am. Acad. Dermatol. 2018 Jun 1; 78 (6): 1135-1141.e3.

BackgroundAlpha-gal syndrome is a hypersensitivity reaction to red meat mediated by IgE antibody specific to galactose-α-1,3-galactose carbohydrate (alpha-gal). Amblyomma tick bites are associated with this condition, but the pathophysiology is not understood.ObjectiveTo clarify the mechanism of development of alpha-gal syndrome after tick bites.MethodsWe compared alpha-gal antibody levels between patients with and without a history of tick bites and examined histologic stainings of tick bite lesions between patients with and without detectable alpha-gal IgE antibody.ResultsPatients who had ≥2 tick bites had higher levels of alpha-gal IgE antibody compared with those with only 1 tick bite or healthy individuals. On histologic investigation, greater numbers of basophils and eosinophils, but not mast cells, were observed infiltrating lesions of patients with ≥2 tick bites compared with those with 1 tick bite. Type 2 cytokine-producing T-cell infiltration was predominantly observed in such patients.LimitationsThe study was conducted at a single institution in Japan.ConclusionIn Amblyomma tick bite lesions, basophils; eosinophils; and type 2, cytokine-producing T cells infiltrate the skin and alpha-gal IgE antibodies are produced. These findings provide a potential mechanistic connection between Amblyomma bites and red meat hypersensitivity.Copyright © 2017 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

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