[Background]: Severe grape allergy has been linked to lipid transfer protein (LTP) sensitization. LTPs are known to be resistant to pepsin digestion, although the effect of gastroduodenal digestion on its allergenicity has not been reported. [Objective]: We sought to investigate the effect of gastric and gastroduodenal digestion on the allergenic activity of grape LTP. [Methods]: The proteolytic stability of grape LTP was investigated by using an in vitro model of gastrointestinal digestion. The allergenicity of LTP and its digesta was assessed in vitro by means of IgE immunoblotting, RASTs, and in vivo skin prick tests in the same patients with grape allergy. [Results]: Grape LTP was resistant to gastric digestion, and yielded a 6000-d relative molecular mass C-terminally trimmed fragment after duodenal digestion. This fragment retained the in vitro IgE reactivity of the intact protein. Inclusion of phosphatidylcholine during gastric digestion protected the LTP to a limited extent against digestion. Digestion did not affect the in vivo (skin prick test) biologic activity of LTP. [Conclusion]: The allergenic activity of grape LTP was highly resistant to in vitro digestion. This property might facilitate sensitization through the gastrointestinal tract and might also potentiate the ability of LTPs to elicit severe allergic reactions in sensitized individuals. [Clinical implications]: Purified natural allergens will facilitate the development of component-resolved diagnostic approaches, including allergen chips. This study contributes to our understanding of the role digestion plays in symptom elicitation in true food allergy.

E. Vassilopoulou was supported through the Institute of Food Research Marie Curie Training Site Fellowship (QLK1-CT-2000-60030) and an Iraklitos fellowship for PhD students (Ministry of Greece for Education and Religions E.P.E.A.E.K II KA 70/3/7148). F. J. Moreno was supported by an EU Marie Curie Fellowship (QLK1-CT-2001-51997). C. Mills and N. Rigby were funded by the BBSRC competitive strategic grant to the Institute of Food Research. L. Zuidmeer and R. van Ree were (partly) funded by a grant from the EC: SAFE QLK1-CT-2000-01394.

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