Evaluation of the cross‐reactivity of antigens in Glupearl 19S and other hydrolysed wheat proteins in cosmetics

BACKGROUND: In Japan, over 2000 users of a facial soap containing Glupearl 19S (GP19S), a hydrolysed wheat protein (HWP), developed immediate‐type systemic wheat allergy (HWP‐IWA), and ∼70% of them developed associated contact urticaria. OBJECTIVES: We investigated whether HWP‐IWA patients cross‐react with other HWPs, and analysed HWP antigenic characteristics. METHODS: We used 10 types of HWP that are commercially available as cosmetic ingredients, and 16 subjects with HWP‐IWA. We performed an enzyme‐linked immunosorbent assay (ELISA) to evaluate the reactivity to each HWP, and western blotting to evaluate the characteristics of the antigens by using HWP‐IWA patients' serum IgE antibodies. We also performed prick tests with the HWPs. RESULTS: The patients reacted to four other HWPs in addition to GP19S, according to ELISA, and this was confirmed by strong reactions in the prick tests to the same four types of HWP. Smears of antigens with molecular weights ranging from the high range to the low range were seen on western blotting with the four HWPs that showed strong reactions in the ELISA and prick tests. CONCLUSIONS: HWP‐IWA patients cross‐react with other HWPs. The antigens that they cross‐reacted to had a molecular weight distribution similar to that of GP19S present in the HWPs.