Consequences of IgE/CD23-mediated antigen presentation in allergy.

Allergen-specific IgE antibodies are responsible for the generation of immediate-type hypersensitivity reactions. However, as described here by Geert Mudde, Roy Bheekha and Carla Bruijnzeel-Koomen, IgE may also be involved in the uptake and processing of allergens. Such IgE-mediated antigen presentation may lead to a continuous (over) activation of the immune system due to high titers of IgE and the presence of large numbers of allergen-specific Th2 cells.

Antigen focusing by specific monomeric immunoglobulin E bound to CD23 on Epstein-Barr virus-transformed B cells.

Monomeric IgE bound to the low-affinity receptor for IgE (FcERII-CD23) on EBV-transformed human B cells selectively enhances binding of antigen and therefore presentation to specific T-cell clones. To demonstrate the role of monomeric IgE in antigen focusing, we have made use of a system consisting of human T-cell clones specific for Der-P1 (major allergen of the Dermathophagoides pteronyssinus), Der-P1 coupled to NIP (Der-P1-NIP), and the commercially available chimeric (human-murine) monoclonal IgE antibodies with specificity for the hapten NIP. We have found that monomeric IgE binds to CD23 and remains detectable on the surface of the B cells for a period of at least 16 hours at 37 degrees C.