Limited IgE cross-reactivity between Dermatophagoides pteronyssinus and Glycyphagus domesticus in patients naturally exposed to both mite species

Background: Contradictory results have been found when analyzing the IgE cross-reactivity among pyroglyphid mites and storage mites, as well as the role of these as true sensitizing agents. Objective: We sought to study the prevalence of sensitization to Glycyphagus domesticus in patients naturally exposed to this mite together with the more ubiquitous Dermatophagoides pteronyssinus and the IgE cross-reactivity between them. Methods: Mite species present in house (lust samples of consecutive patients with mite allergy from Huelva (southwest Spain) were determined by means of light microscopy. Clinical sensitization was assessed by using skin prick and conjunctival provocation tests. Cross-reactivity at the IgE level was studied by using serum IgE determination and inhibition of RAST, IgE immunoblotting, and mite group 2 immunoassays. Results: After D pteronyssinus, which is present in about 95% of house dust samples, G domesticus was the most important mite and present in about 50% of the samples. Tyrophagus putrescentiae and Lepidoglyphus destructor were detected in third and fourth place, respectively. About half of the patients with G domesticus at home were sensitized to this mite. A low IgE cross-reactivity was observed between D pteronyssinus and G domesticus, but an important IgE cross-reactivity was detected among glycyphagid mites at the level of group 2 allergens. C onclusion: Glycyphagid mites can act as primary sensitizing agents independently of pyroglyphid mites in a subset of patients naturally exposed to them. Clinical implications: The inclusion of glycyphagid mite extracts in the diagnostic battery in areas with adequate mite growing conditions is important to ensure proper diagnosis.