IgE epitopes are within the hydrophobic domain of sesame oleosin Ses i 4

Aim of the study

Oleosins are allergens implicated in severe anaphylactic reactions after sesame, peanut or hazelnut consumption. However, identifying oleosin allergenic epitopes is hindered by their hydrophobic properties that do not allow analysis in an aqueous solution. Therefore, the present study focused on determining IgE-binding domains of sesame oleosin Ses i 4 using immunoblotting.

Patients and methods

We relied on sera from ten patients with clinically established allergy to sesame. Immunoblotting coupled to Hydrophobic Cluster Analysis (HCA) approach using a series of recombinant full-length and truncated Ses i 4 variants enabled detection of IgE reactivity domains.

Results and conclusion

The data showed that IgE-binding sequences were located in the hydrophobic domain of the Ses i 4. The three IgE-binding segments were in proximity but on the flanks of the central-most hydrophobic segment. Further, their amino acid sequences are highly conserved in Ses i 4-homologs from different allergenic sources. Therefore, unlike most clinical immunoassays, Western blotting may be helpful for in vitro detection of oleosin IgE reactivity.