Cross-allergenicity between Aspergillus restrictus, Aspergillus fumigatus and Alternaria alternata determined by radioallergosorbent test inhibition

Aspergillus restrictus, an osmophilic fungus, is abundant in house dust. We have shown previously that the incidence of immediate hypersensitivity to A. restrictus is comparable to that for Aspergillus fumigatus and Alternaria alternata in asthmatic children. Radioallergosorbent test (RAST) inhibition was used to determine whether A. restrictus shares similar allergenic components with A. fumigatus and A. alternata. Mycelial mats of the three species cultivated on completely synthetic media were used for extract preparation. IgE antibodies to each fungus were measured with RAST using a polyvinyl chloride microplate as a solid phase. Analysis of a serum pool obtained from nine asthmatic children with a positive RAST to A. restrictus showed that A. restrictus inhibited the RAST to A. restrictus, A. fumigatus and A. alternata by more than 80%. Similar results were observed with A. fumigatus and A. alternata. Additionally, when 13 serum samples with a positive RAST to A. restrictus were tested separately, A. restrictus substantially inhibited the A. restrictus RAST in all subjects tested. A. fumigatus and A. alternata inhibited the A. restrictus RAST in 10 and 8 of the samples studied, respectively. These findings indicate that A. restrictus shares allergenic components with A. fumigatus and A. alternata. The allergenic cross-reactivity between A. fumigatus and A. alternata was also demonstrated.