Synthetic amorphous silica nanoparticles (SAS-NPs), present in many everyday products, appear as a signal of immunological danger by increasing the maturation of dendritic cells (DCs) and the response of T lymphocytes (TL) [Feray2020, Feray2021]. We recently demonstrated the major role of the interaction between SAS-NPs and DC membranes in this process [Guillet2023].

Given that co-exposures to allergens and nanomaterials are highly likely, we investigated the adjuvant potential of SAS-NPs in respiratory allergy, using Bet v 1a, the main allergen of birch pollen, as a model, which was produced and purified at ICP. This project has been supported by ANSES funding (Allergosil project 2020-2024).

Using an autologous co-culture model with human naive CD4+ T cells and DCs, we showed that the frequency of CD4+ T cells recognizing Bet v 1a was higher when DCs were exposed to the allergen in the presence of SAS-NPs, confirming their adjuvant effect. We then quantified the intracellular levels of Bet v 1a in DCs by Western blot and demonstrated that concomitant or sequential exposure to SAS-NPs increases allergen internalization. Using dynamic light scattering and circular dichroism, we demonstrated an in vitro interaction between Bet v 1a and SAS-NPs, which could, if it persists under DC exposure conditions, influence its internalization and fate within the cell.