Hypoallergenic hydrolysates of egg white proteins modulate allergen responses induced ex vivo on spleen cells from sensitized mice

- The hydrolysate of ovalbumin with pepsin is hypoallergenic in vivo.
- It induces a lower Th2 activation of spleen cells of sensitized mice than ovalbumin.
- The hydrolysate can down-regulate the Th2 responses induced by egg allergens.
- The hydrolysate can enhance Th1 responses.
- It can find applications for the treatment of egg allergy.

This study describes the in vivo allergenicity of enzymatic hydrolysates of egg white proteins (ovalbumin, lysozyme and ovomucoid) and explores the possibility that they could modulate T cell cytokine responses to egg allergens ex vivo, using splenocytes from BALB/c mice sensitized to individual egg proteins or to their mixtures in different proportions. The hydrolysate of ovalbumin with pepsin could be regarded as a good candidate for peptide-based immunotherapy on the grounds of its reduced ability to trigger allergic symptoms in a passive cutaneous anaphylaxis assay and its potential to reduce Th2 responses (release of IL-4 and IL-5) induced by egg allergens in the spleen cell cultures, but also to enhance Th1 responses (release of TNF-α and IFN-γ). While it is possible to obtain chromatographic fractions containing peptides with different Th2-inhibiting or promoting properties, as judged by cytokine production, selective peptide enrichment did not lead to an increase in the immunomodulating efficiency as compared with the whole ovalbumin hydrolysate, possibly due to the presence in the latter of a combination of immunogenic peptides with synergistic or adjuvant actions.

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