The allergenic structure of the thaumatin-like protein Ole e 13 is degraded by processing of raw olive fruits.

BACKGROUND The thaumatin-like protein (TLP) Ole e 13 in raw olive fruit is responsible for occupational allergy in olive oil mill workers. However, these workers do not experience allergic symptoms after ingestion of edible olive. OBJECTIVES To analyze the presence of IgE-reactive TLP in raw and edible olive fruit and to assess the allergenic potency of both sources. METHODS The content of TLP in raw and edible olive fruit protein extracts was analyzed using immunoblotting with sera from allergic patients and with olive TLP-specific IgG. The structural and immunological stability of TLP were assayed using immunoblotting after treatment of both raw olive and purified TLP with 0.25 M NaOH solution for 24 hours. Olive pollen extract was investigated by immunoblotting for TLP content. RESULTS The TLP contained in raw olive fruit was not present in edible olives as a result of maceration before human consumption. No TLP was detected in olive pollen using specific IgG or sera from patients allergic to olive fruit. Sera from patients allergic to olive pollen did not react with purified TLP. CONCLUSIONS IgE-reactive TLP is not present in edible olive, thus explaining the low number of patients allergic to this highly consumed fruit. Patients allergic to olive pollen are not sensitized toTLP and, therefore, not expected to be at risk of food allergy to olive fruit or TLP plant sources.