Conglutin-γ in lupin allergy: interaction with dendritic cells and cytokine production

Lupin belongs to the legume family and may give rise to allergic reactions in sensitive people. With the spreading use of lupin-based foods, an increasing number of adverse reactions due to the presence of certain proteins have been reported. The knowledge of the relationships between the structure of these proteins and their potential in triggering allergenicity and of the mechanisms of action at the cellular level that cause the onset of the allergic reaction is of utmost importance for developing new food technologies capable of mitigating allergic reactions. In this study, we focused on the glycoprotein conglutin-γ (Cg), considered one of the major allergens of lupin seed. We investigated the effect of Cg on murine bone marrow-derived dendritic cells evaluating the production of cytokines in the presence and absence of inflammatory stimuli. In particular, the interaction of Cg with the cells enhanced the IL-23 production induced by E. coli LPS in a dose-dependent manner, while IL-12 production was reduced. On the contrary, the Gram-positive bacteria Lactobacillus acidophilus str. NCFM induced an increase in both IL-12 and IL-23 production. Moreover, treating the cells with only Cg did not affect the upregulation of maturation markers and therefore the cell does not begin to migrate to the lymph nodes. Finally, flow cytometry experiments showed the capacity of the dendritic cells to internalize Cg. In conclusion, this study provides evidence that Cg may potentially modulate the cytokine production in BMDCs induced by bacteria and is endocytosed by dendritic cells, probably through a mechanism mediated by the mannose residues of the glycosidic moiety of the protein.