Api m 6: A new bee venom allergen

Background: Characterization of the primary structure of allergens is a pre requisite for the design of new diagnostic and therapeutic tools for allerg ic diseases. Objective: The purpose of this study was the identification and characteriz ation of a low-molecular-weight, IgE-binding, bee venom (BV) allergen. Methods: BV proteins were separated by using size exclusion chromatography and HPLC, IgE antibody binding to purified proteins was analyzed by means o f immunoblotting, and T-cell response was analyzed by means of proliferatio n assay. Amino acid sequence was determined with 2 approaches, namely Edman degradation and carboxy terminal analysis with mass spectrometry, Results: Api m 6, which migrated as an 8-kd band in SDS-PAGE, was frequentl y (42%) recognized by IgE from BV-hypersensitive patients, In addition, PBM Cs from BV-hypersensitive patients, as well as from a normal control subjec t, proliferated in response to this allergen. Api m 6 exists as 4 isoforms of 7190, 7400, 7598, and 7808 d, respectively. Amino acid sequences obtaine d from HPLC-purified preparations revealed that the isoforms were constitut ed of a common central core of 67 residues, only differing in the amino- an d carboxy-terminal ends, Api m 6 showed no significant sequence homology wi th known proteins. Conclusions: We have Identified and sequenced a new BV allergen that elicit s a strong IgE and T-cell response in a large number of BV-hypersensitive p atients. Api m 6 should be considered in the diagnostic and therapeutic app roach of BV immunotherapy on the basis of peptides or recombinant proteins.