Comparison of clinical significance and allergenic cross‐reactivity of storage mites Blomia kulagini and Lepidoglyphus destructor in Sweden and Brazil

Comparison of the clinical significance and allergenic cross‐reactivity of Blomia kulagini(B. kulagini) and Lepidoglyphus destructor (L. destructor) was made on sera from Sweden and Brazil using the radio‐allergo‐sorbent test (RAST) and the RAST inhibition technique. RAST‐positive sera were obtained from 53 allergic Swedish farmers and 31 allergic subjects from Brazil who were positive to B. kulagini and/or L. destructor. B. kulagini was shown to be a common cause of sensitization especially in Brazil. There was a fairly high correlation between positive RAST results to L. destructor and B. kulagini based on sera from both Sweden and Brazil. The highest RAST scores were found against L. destructor in Swedish sera and against B. kulagini in Brazilian sera. The RAST inhibition studies showed that the L. destructor extract was able to inhibit the B. kulagini system (a positive RAST to B. kulagini allergen disc) in Swedish but not in Brazilian sera. In contrast, the B. kulagini extract was only able to inhibit the L. destructor system in sera from Brazil and not in sera from Sweden. This study shows that results obtained with RAST inhibition are not entirely dependent on the overall specificity of the IgE antibodies in the patient's sera, since the more subtle specificity of the primarily sensitizing allergen will dominate. Thus, conclusions drawn regarding allergenic cross‐reactivity are dependent on the populations tested, and conclusions on the existence or absence of cross‐reactivity, e.g. between two species of mites may be contradictory.