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Children with problematic severe asthma (PA) have persistent symptoms and/or severe exacerbations despite treatment with several drugs. Classification of asthma severity is currently based on level of treatment and assessment of asthma control, but objective biomarkers of asthma severity are needed. To investigate the clinical relevance of basophil allergen threshold sensitivity (CD-sens) as a measure of allergen sensitivity in a well-characterized cohort of children with different manifestations of persistent allergic asthma. Cat-allergic children (6-18 yr) with problematic severe asthma (n = 11) according to GINA were compared with eleven age-matched children with controlled, but persistent asthma (CA). The protocol included standardized questionnaires, asthma control test (ACT), spirometry, methacholine challenges, measurement of FE(NO,) IgE, cat IgE and IgG antibodies, and analysis of CD-sens (CD63-expression) by flow cytometry. The 11 cat-allergic children with PA had a significantly lower ACT score (p < 0.001), reduced FEV(1) (p = 0.04), and increased numbers of blood eosinophils (p = 0.03) compared with the 11 children with CA. The former exhibited a higher CD-sens to cat (p = 0.02). No significant differences were detected with respect to FE(NO) (p = 0.17), IgE (p = 0.84), cat IgE (p = 0.12), and the major cat-allergen rFel d 1 (p = 0.30). CD-sens significantly correlated with ACT (p = 0.002, r = -0.63) and FE(NO) (p = 0.01, r = 0.55). No significant differences between PA and CA were found regarding IgG antibodies to rFel d 1. Cat-allergic children with problematic severe asthma have higher sensitivity to cat allergen, as measured by CD-sens, compared with children with controlled asthma. This suggests that CD-sens could be used as an additional marker for identifying children with the most severe allergic asthma., (© 2011 John Wiley & Sons A/S.)

Background: Five to ten percent of the population in affluent countries are allergic to dog. Diagnosis and treatment is based on allergen extracts from natural sources where composition and concentration are poorly defined. Objective: We aimed to quantify six dog allergens (Can f 1‐6) in commercial skin prick test (SPT) solutions and to determine individual allergen profiles in dogs. Method: The allergen content of SPT solutions from five vendors and allergen source material from three anatomical sites were analyzed. Fur and saliva samples were collected from a mixed population of 120 dogs. Can f 1‐6 were quantified by inhibition ELISA using purified recombinant or natural allergens and polyclonal or monoclonal antibodies. Allergenicity was analyzed by basophil activation test. Results: Extensive variation in allergen composition was observed in commercial SPT vials resulting in a patient‐dependent ability to activate basophils. Extract heterogeneity depended on collection site and allergen composition in individual dogs and source materials. Can f 2 and Can f 6 exhibited low levels in fur and SPT solutions, whereas Can f 4, which was the dominating allergen in fur samples, did not display similar high proportions in SPT solutions. Can f 3 varied most among SPT solutions. Conclusion: There is a great variation of dog allergens in natural extracts raising questions of source, sampling, processing and ultimately of standardization and minimum allergen levels for accurate diagnosis and treatment. [ABSTRACT FROM AUTHOR]