HUMAN AUTOANTIIDIOTYPIC ANTIBODIES TO MITE-SPECIFIC IGE CAN DEGRANULATE HUMAN BASOPHILS IN-VITRO

Background Anti-idiotypic antibodies (anti-Ids) to specific IgE antibo dies are formed spontaneously during an anti-allergen immune response and can be induced by immunotherapy. Although anti-Ids can down-regula te the production of IgE antibodies, at least in experimental models, their possible role in the modulation of target cell reactivity remain s ill-defined. Objective The capacity of human anti-Ids to modulate th e release of histamine was examined in an in vitro system of human bas ophil degranulation. Anti-Ids were prepared from the serum of six Derm atophagoides pteronyssinus (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 histamine rel ease was determined using a fluorometric assay. Results We show that a nti-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 activi ty can be removed by absorption with affinity-purified anti-Dp antibod ies of the corresponding patient. Conclusion These results indicate th at spontaneously produced human anti-Ids can modulate the reactivity o f human basophils.