The Western blot is a highly sensitive and efficient technique in diagnosing allergy to wasp venom

Background Diagnosis of allergy to wasp venom and decision to perform immun otherapy are based on the patient's history, along with skin and in vitro t ests. Objective Given the high prevalence of specific IgE also in non-allergic in dividuals, we evaluated the sensitivity and specificity of Western blots as a possible alternative to serum analyses of venom-specific IgE. Methods Skin prick and/or intracutaneous tests were performed in 30 patient s with allergy to wasp venom (generalized reaction following sting) along w ith serum analysis of venom-specific IgE (AIaSTAT microplate) and Western b lots. Western blots were subsequently scanned and evaluated qualitatively a nd semiquantitatively by means of densitometry. Bands were scored 'positive ' in cases of signal intensities beyond the mean plus 3 standard deviations of control sera. Twenty newborns (age 2-7 days) and 30 adults without syst emic or increased local reactions to hymenoptera stings served as controls. Results Western blot sensitivity reached 100% in the samples studied and wa s thus superior to the sensitivities of serum analysis of venom-speck IgE u sing AlaSTAT microplate assay (90%) and skin tests (87%). The sensitivity o f detection of a phospholipase A1 and antigen 5-specific band was higher co mpared with a hyaluronidase-specific band (97%, 97% and 86%, respectively). Twenty-four out of twenty-nine (83%) patients exhibited specific IgE antib odies against at least three distinct allergens. With regard to the specifi cities, skin tests as well as AIaSTAT microplate assays were comparable (90 % and 93%, respectively), whereas the spec city of the Western blots was 70 % if the appearance of any single band was regarded as a positive result. H owever, when analysing the appearance of a specific band for antigen 5 or h yaluronidase the specificity and overall diagnostic value increased markedl y, making it the most efficient test (specificity 97% and 100%, efficiency 96.8% and 93.2%, respectively). Conclusion As allergy to wasp venom is a severe and potentially life threat ening disease, false-negative test results need to be minimized. Therefore, the superiority of the Western blot with regard to sensitivity, specificit y and overall efficiency makes this technique a valuable tool for its diagn osis.