Characterization of folded recombinant Der p 5, a potential diagnostic marker allergen for house dust mite allergy

• <i>Background:</i> Der p 5 was reported as an important allergen in<i> Dermatophagoides pteronyssinus</i>, which is particularly recognized by patients suffering from asthma. The aim of this study was to produce, by recombinant DNA technology, a folded Der p 5 allergen for diagnostic, therapeutic and preventive purposes. <i>Methods:</i> Der p 5-encoding cDNA was isolated from a λgt11 <i>D. pteronyssinus</i> expression cDNA library and expressed in <i>Escherichia coli</i>. rDer p 5 was purified to homogeneity and characterized by mass spectroscopy and circular dichroism. IgE reactivity was tested with sera from 117 mite-allergic patients and in a basophil histamine release experiment. Der p 5-specific rabbit IgG antibodies were produced for the ultrastructural localization of the allergen in mites by immunogold electron microscopy as well as for cross-reactivity studies. <i>Results:</i> rDer p 5 is a heat-stable protein with predominantly α-helical secondary structure which reacted with IgE from 31% of mite-allergic patients’ sera and showed no relevant cross-reactivity to group 5 allergens from storage mites and tropical mites. rDer p 5-specific rabbit IgG antibodies inhibited mite-allergic patients’ IgE binding to Der p 5 and allowed to localize the allergen in secretory granules of midgut epithelial cells of house dust mites. <i>Conclusions:</i> The described rDer p 5 molecule may be useful for diagnosis and immunotherapy of house dust mite-allergic patients.

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