Cross‐reactive carbohydrate determinants strongly affect the results of the basophil activation test in hymenoptera‐venom allergy

Background In hymenoptera‐venom allergy, sera of up to 60% of patients show in vitro reactivity to honeybee venom (HBV) and yellow jacket venom (YJV). This phenomenon is mainly caused by specific IgE (sIgE) against cross‐reactive carbohydrate determinants (CCD). Whether or not these antibodies can induce clinical symptoms is a longstanding debate. Objective The aim of this study was to investigate the biological activity of CCD‐sIgE and the suitability of the basophil activation test (BAT) in hymenoptera venom‐allergic patients having CCD‐sIgE. Methods The biological activity of CCD‐sIgE was analysed by application of native and CCD‐depleted YJV and HBV in BAT with the blood of 62 hymenoptera venom‐allergic patients and 16 non‐allergic controls. According to results of intracutaneous skin tests (IC) with YJV and HBV and the existence of CCD‐sIgE, patients were classified into six subgroups. Results In patients with mono‐positive IC and CCD‐sIgE, and thus double‐positive sIgE, BAT with native venoms was also double positive in up to 67% of the patients. In contrast, BAT with CCD‐depleted venoms was positive only with the IC‐positive venom. However, activation of basophils with the IC‐negative venom was significantly lower compared with the IC‐positive one. In IC mono‐positive patients without CCD‐sIgE, BAT was mono‐positive with the IC‐positive venom in the native and in the CCD‐depleted form. CCD‐positive patients with double‐positive IC were a heterogeneous group, with the majority of CCD‐positive patients also being double positive with the native forms of both venoms but mono‐positive with the CCD‐depleted ones. Conclusions In vitro BAT clearly demonstrates biological activity of CCD‐sIgE. However, because most of the patients showed a mono‐positive IC and activation of basophils with the IC‐negative venom was significantly lower compared with the IC‐positive one, the present data suggest that CCD‐sIgE is clinically irrelevant in these patients. Cite this as: M. Mertens, S. Amler, B. M. Moerschbacher and R. Brehler, Clinical & Experimental Allergy, 2010 (40) 1333–1345.