Basophil allergen threshold sensitivity, CD-sens, is a measure of allergen sensitivity in asthma

Background Allergic asthma is IgE-mediated and the IgE-sensitisation is usually demonstrated by skin prick tests (SPT) and IgE antibody determinations in serum. The SPT and IgE-antibody values do not directly predict if the allergy clinically contributes to the asthma. There is therefore a need for new objective tests that may indicate the clinical importance of an IgE-sensitisation. Objective To evaluate basophil allergen threshold sensitivity (CD-sens) as a measure of allergen sensitivity in allergic asthma. Methods Twenty-six subjects with stable, intermittent allergic asthma were tested with SPT and spirometry, and methacholine and allergen inhalation challenges to determine methacholine PD20 (provocative dose causing a 20% drop in forced expiratory volume in 1 s) and allergen PD20. The results were compared with CD-sens and serological parameters, i.e. IgE- and IgG4 antibodies to the relevant allergens. Results A significant correlation was found between CD-sens and allergen PD20 (P = 0.01; r = 0.49; n = 26) as well as between CD-sens and the ratio of allergen PD20 to methacholine PD20 (P = 0.007; r = 0.52; n = 26). In patients with a moderate to low degree of bronchial hyperresponsiveness there was an excellent correlation (P = 0.0001; r = 0.88, n = 13) between CD-sens and allergen sensitivity. No relation to either allergen PD20 or the ratio was found for basophil allergen reactivity measured as CD63 up-regulation at high concentrations of the respective allergen. Conclusions and Clinical Relevance CD-sens was found to be an objective marker of airway allergen sensitivity in stable allergic asthmatics, that may be used to predict airway responsiveness when bronchial challenge tests cannot be performed.