Human auto-anti-idiotypic antibodies to mite-specific IgE can degranulate human basophils in vitro

Background Anti-idiotypic antibodies (anti-Ids) to specific IgE antibodies are formed spontaneously during an anti-allergen immune response and can be induced by immunotherapy. Although anti-Ids can down-regulate the production of IgF. antibodies, at least in experimental models, their possible role in the modulation of target cell reactivity remains ill-defined. Objective The capacity of human anti-Ids to modulate the release of histamine was examined in an in vitro system of human basophil degranillation. Anti-Ids were prepared from the serum of six Dermatophagoides pteranyssinus (DP)-hypersensitive patients suffering from atopic dermatitis and who had never been desensitized. Basophils were obtained from the blood of atopic donors. The extent of histaminc release was determined using a fluorometric assay. Results We show that: anti-Ids trigger the release of histamine in an allergen-specific, dose- and IgE-dependent manner; the release is not due to the presence of allergen and/ or anti-IgE antibodies: and that the degranulating activity can be removed by absorption with affinity-purified anti-Dp antibodies of the corresponding patient. Conclusion These results indicate that spontaneously produced human anti-Ids can modulate the reactivity of human basophils.