Wheat lipid transfer protein is a major allergen associated with baker's asthma

Background: Baker's asthma is a frequent occupational allergic disorder mainly caused by inhalation of cereal flours. Lipid transfer proteins (LTPs) constitute a family of plant food panallergens, but their role as inhalant and wheat allergens is still unclear. Objective: We sought to explore the involvement of wheat LTPs in baker's asthma caused by wheat flour sensitization. Methods: Forty patients with occupational asthma caused by wheat flour inhalation were studied. Wheat UP, Tri a 14, was purified by using a 2-step chromatographic protocol and characterized by N-terminal amino acid sequencing and 3-dimensional modeling. Its reactivity was confirmed by means of IgE immunodetection, ELISA and ELISA-inhibition assays, and skin prick tests. Results: Specific IgE to Tri a 14 was found in 60% of 40 individual sera from patients with baker's asthma, and the purified allergen elicited positive skin prick test reactions in 62% of 24 of these patients. Tri a 14 and peach UP, Pru p 3, showed a sequence identity of 45%, but the low cross-reactivity between both allergens detected in several individual sera reflected great differences in their 3-dimensional IgE-binding regions. Conclusions: Wheat UP is a major inhalant allergen associated with baker's asthma caused by wheat flour sensitization. Poor cross-reactivity with its peach homolog was found in some patients. Clinical implications: LTPs can be considered relevant inhalant allergens linked to respiratory disorders. UP from wheat (Tri a 14) can be used as a helpful tool for the diagnosis of baker's asthma.