D1.282 - Identification of Thaumatin-like protein (Ole E 13) as a potential allergen in green olives, a case report

Introduction  

Olives, a hallmark of the Mediterranean diet, are widely consumed worldwide in various forms. Despite their nutritional and cultural importance, reports of olive-induced allergic reactions are rare and poorly characterised. Allergic reactions to olive pollen are well documented, with allergens such as Ole e 1 and Ole e 13 (thaumatin-like protein, TLP) identified as major contributors. However, little is known about the allergenic potential of olive fruit proteins, particularly in green olives.

Materials and Methods

This study investigates the case of a 25-year-old woman with generalized pruritus, nasal congestion and itching of the scalp immediately after eating green olives stuffed with anchovies. The symptoms disappeared within an hour after treatment with antihistamines. Subsequent episodes of similar reactions have been reported with unstuffed green olives. 

Prick-Prick test was performed with green olive provided by the patient. 

Green olive extracts provided by the patient were processed using protein extraction protocols including acetone precipitation, centrifugation and SDS-PAGE separation. Western blot analysis of IgE was performed to identify allergenic proteins using the patient's serum. The bands detected were analysed for molecular weight match with known olive allergens. 

Results

Skin Prick-Prick tests showed a positive reaction to green olive (4x4 mm) and profilin extract (3x7 mm), but no reactivity to black olives or lipid transfer proteins (LTPs). Serum IgE was elevated (194 IU/mL). 

Western blot analysis identified a prominent IgE-reactive protein band at approximately 23 kDa, consistent with the molecular weight of Ole e 13 (TLP). No other major reactive bands were observed. These findings implicate Ole e 13 as the likely trigger of the patient’s allergic reactions to green olives. 

Conclusions 

This study confirms the presence of Ole e 13 in green olives as a potential allergen. Further research is needed to validate these findings and explore cross-reactivity with other allergenic sources. These insights contribute to improved diagnosis and management strategies for olive-related allergies.