Biochemical and immunological analysis of mould skin prick test solution: current status of standardization
Article first published online: 24 OCT 2013
© 2013 John Wiley & Sons Ltd
Clinical & Experimental Allergy
Volume 43, Issue 11, pages 1286–1296, November 2013
How to Cite
Clinical & Experimental Allergy, 2013; (43) 1286–1296., , , , , .
- Issue published online: 24 OCT 2013
- Article first published online: 24 OCT 2013
- Accepted manuscript online: 20 AUG 2013 10:01AM EST
- Manuscript Accepted: 14 AUG 2013
- Manuscript Revised: 1 AUG 2013
- Manuscript Received: 9 APR 2013
- allergen content;
- mould allergen extracts;
- skin prick test;
Sensitization prevalence to moulds reached from less than 10% in the general population to more than 25% in atopic and/or asthmatic subjects. To diagnose IgE-mediated mould sensitization, skin prick test (SPT) and specific IgE (sIgE) measurement are recommended. However, concordance of SPT and sIgE results is often less than 50% and standardization of the extracts is required to achieve reliable test results.
The aim of our study was to analyse mould SPT solutions (SPTs) with respect to quantity and quality of protein, antigen and human IgE-binding content as a prerequisite for further in vivo studies.
Commercial SPTs of Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum and Penicillium chrysogenum from six manufacturers as well as two in-house extracts from Aspergillus versicolor were investigated. Protein-, antigen- and IgE-binding contents were quantified by Bradford assay, sandwich ELISA and IgE-ImmunoCAP-inhibition tests. Protein composition and IgE and IgG binding were analysed by SDS-PAGE and immunoblotting, respectively.
Median protein concentrations were similar in all mould SPT extracts (90–110 μg/mL). In contrast, antigen contents and IgE-binding capacity showed a high variability with median antigen values from 4 to 118 μg/mL and IgE inhibition results between 30 to 95%. Whereas almost all SPTs of A. alternata and A. versicolor showed complete sIgE inhibition with mean values > 80%, only three extracts for A. fumigatus, two extracts for C. herbarum and none of the tested extracts for P. chrysogenum exceeded 50% sIgE reduction. Quantitative amounts of protein, antigenic and IgE-binding structures were not comparable with the quality of the corresponding protein or immunoblot pattern, with the exception of A. alternata SPTs.
Conclusions and Clinical Relevance
Commercially available mould SPT extracts showed high variability raising the question of comparability and reliability of SPT results. Possible consequences for diagnostic test outcome will be investigated in the next step.