Development of a Dot-Blot Assay for the Detection of Mould-Specific IgE in the Belgian Population

Background Data on mould sensitization in the general population are scarce and mostly on Aspergillus fumigatus, Alternaria alternata and Cladosporium herbarum. Objectives To validate a dot-blot assay for the detection of specific IgE and evaluate the prevalence of mould sensitization in a healthy population. Methods The dot-blot assay was validated against the CAP test. Sensitization rate to ten common indoor and outdoor mould species in 344 serum samples was calculated. For each serum with more than one reactivity, the major sensitization'' defined as the strongest response against a single mould species was calculated. Results Intra-and inter-assay variations were both below 20%, and the positivity threshold of the test was of 0.418 kU/L for A. fumigatus. Correlation with CAP results was strong. The overall prevalence of sensitization was 32.8%, and the commonest sensitizations were against A. alternaria, A. flavus and A. niger (around 15%). The most frequent major reactivities'' were against A. niger and A. alternata (20-30%). In 25.1% of the samples, major reactivities'' were directed against a group of moulds commonly found indoor (Penicillium spp., Aspergillus versicolor, Cladosporium sphaerospermum and Cladosporium cladosporioides). Conclusions The dot-blot assay was validated for the detection of mould-specific IgE. In the general population, sensitization to indoor species was common and accounted for 25% of overall mould sensitizations.