Food allergens are protected from degradation during CD23-mediated transepithelial transport

Background: CD23 (FcepsilonRII) is expressed by intestinal epithelial cells (IEC) following allergic stimulation and increases the uptake of IgE/allergen complexes. The aim of this study was to further analyze the role of CD23 in the intraepithelial processing of food allergens during transepithelial transport. Methods: Balb-C mice were sensitized intraperitoneally with horseradish peroxidase (HRP) or beta-lactoglobulin (beta-LG) in the presence of pertussis toxin. In control and sensitized mice, H-3-HRP, intact HRP, or C-14-beta-LG fluxes were measured across jejunal segments mounted in Ussing chambers, in the presence or absence of mucosal anti-CD23 antibodies. HPLC analysis of serosal buffer was performed to detect HRP- or beta-LG-derived radiolabelled metabolites generated during transepithelial transport. Results: In HRP-sensitized mice, H-3-HRP fluxes and intact HRP fluxes (3,836+/-476 and 290+/-86 ng/h.cm(2), respectively) were significantly increased compared to control mice (1,677+/-297 ng/h.cm(2), p<0.01, and 106 +/- 23 ng/h.cm(2), p<0.02, respectively). HPLC analysis indicated the presence of intact HRP in the serosal compartment already 10 min after addition of HRP to the mucosal compartment, a result not observed in the control mice. In the presence of anti-CD23 antibodies, intact HRP fluxes were significantly decreased (131+/-27 ng/h.cm(2)) compared to control values in sensitized mice (290+/-86 ng/h.cm(2), p<0.02), suggesting that CD23 is involved is this 'protected' transport pathway. A similar protection during intestinal transport was observed for beta-LG in beta-LG sensitized mice. Conclusions: These results confirm that CD23 is involved in the rapid transepithelial transport of intact allergens in sensitized animals, and indicate that CD23 opens a 'protected' transport pathway in IECs. Copyright (C) 2004 S. Karger AG, Basel.