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Background Lipids are required for mice sensitization to Ber e 1, Brazil nut major allergen. Here, we characterized different lipid fractions extracted from Brazil nuts and the lipid-binding ability of Ber e 1. Further, we determined their in vivo ability to induce Berspecific anaphylactic antibodies and the role of invariant natural killer T (iNKT) cells in this process.Methods Wild-type (WT) and iNKT cell-deficient mice were sensitized with Ber e 1 and specific lipid fractions, and anaphylactic antibodies were measured by enzyme-linked immunosorbent assay (ELISA) and passive cutaneous anaphylaxis (PCA). The lipid-binding characteristic of Ber e 1 (Ber) was established by using fluorescent probes and 15N-labeled NMR. In vitro production of IL-4 was determined in Ber/lipid C-stimulated mouse iNKT cells and human T-cell lines containing NKTs primed with CD1d+C1R transfectants by flow cytometry and ELISA, respectively.Results Only one specific lipid fraction (lipid C), containing neutral and common phospholipids, induced Ber anaphylactic antibodies in mice. Ber e 1 has a lipid-binding site, and our results indicated an interaction between Ber e 1 and lipid C. iNKT-deficient mice produced lower levels of anaphylactic antibodies than WT mice. In vitro, Ber/lipid C-stimulated murine iNKT cells produced IL-4 but not IFN-gamma. Human T-cell lines derived from nut-allergic patients produced IL-4 to Ber/lipid C in a CD1d- and dose-dependent manner.Conclusion Lipid fraction C from Brazil nut presents an essential adjuvant activity to Ber e 1 sensitization, and iNKT cells play a critical role in the development of Brazil nut-allergic response.
Background Lipids are required for mice sensitization to Ber e 1, Brazil nut major allergen. Here, we characterized different lipid fractions extracted from Brazil nuts and the lipid-binding ability of Ber e 1. Further, we determined their in vivo ability to induce Berspecific anaphylactic antibodies and the role of invariant natural killer T (iNKT) cells in this process. Methods Wild-type (WT) and iNKT cell-deficient mice were sensitized with Ber e 1 and specific lipid fractions, and anaphylactic antibodies were measured by enzyme- The lipid-binding characteristic of Ber e 1 (Ber) was established by using fluorescent probes and 15N-labeled NMR. In vitro production of IL-4 was determined in Ber / lipid C-stimulated mouse iNKT cells and human T-cell lines containing NKTs primed with CD1d + C1R transfectants by flow cytometry and ELISA, respectively. Results only one specific lipid fraction (lipid C), containing neutral and common phospholipids, induced Ber anaphylactic antibodies in mice. Ber e 1 has a lipid-binding site, and our results indicated an interaction between Ber e 1 and lipid C. iNKT-deficient mice produced lower levels of anaphylactic antibodies than WT mice. In vitro T-cell lines derived from nut-allergic patients produced IL-4 to Ber / lipid C in a CD1d-and dose-dependent manner .Conclusion Lipid fraction C from Brazil nut presents an essential adjuvant activity to Ber e 1 sensitization, and iNKT cells play a critical role in the development of Brazil nut-allergic response.