D3.200 - Broad profile of olive pollen sensitisation as a key factor in immunotherapy failure

Olive pollen (Olea europaea) is a major cause of seasonal respiratory allergy in Mediterranean regions. Although immunotherapy is usually effective, some patients continue to experience symptoms due to broad sensitization profiles that include minor allergens not routinely represented in commercial extracts. This report describes a patient with recurrent asthma exacerbations during the olive pollen season despite completing five years of polymerized Olea immunotherapy and provides a detailed molecular characterization of the sensitization pattern.

A 37-year-old patient who has been undergoing 100% Olea polymerised immunotherapy (IT) for 5 years from 3 different commercial companies. Every year, she experiences an exacerbation of asthma in May, so she goes to emergencies even though she is undergoing IT. The molecular characterisation included ALEX² test, standardized Olea europaea protein extraction, SDS-PAGE, IgE–Western blot, and ALEX² inhibition using olive pollen extract.

In previous reports, analysis with specific IgE Olea prior to IT was over 100 UI/L, and after 3 years of IT the same levels are maintained. However, after completing the 5 years of IT, the sIgE levels obtained by the ALEX² test were 40.53 kU/L for Ole e 1, Ole e7 45,5 kU/L and 29.21 kU/L for Ole e 9. Western blot revealed an extensive allergy profile with bands ranging from 10 to 50 kDa. The strongest bands corresponded to Ole e 1 at 16–18 kDa, Ole e 7 at ~10 kDa and Ole e 9 at ~40 kDa,in agreement with the ALEX² profile. Beyond these major allergens, clear recognition of several minor Olea proteins was observed, including Ca²⁺-binding polcalcins Ole e 3 and Ole e 8 (9–20kDa), as well as Ole e 2 (~14 kDa), Ole e 4 (~32 kDa), Ole e 6 (~10 kDa), Ole e 10 (~10 kDa), and a broader reactivity pattern consistent with Ole e 11, 12, 13 and 14. The ALEX² inhibition assay showed marked reduction in IgE binding to Ole e 1, Ole e 7 and Ole e 9, and complete inhibition of Phl p 7 and Aln g 4, confirming substantial cross-reactivity between olive allergens and homologous proteins from grasses and alder.

the patient showed a very intense and complex sensitisation profile, with recognition not only of the most prevalent and best characterised allergens such as Ole e 1, 7 and 9, but also of other minor and less characterised allergens.Consequently, the choice of a suitable olive pollen extract containing all the potentially allergenic proteins to which the patient is sensitised is key to the patients treatment.