BIOLOGICAL-ACTIVITY OF RECOMBINANT DER-P-2, DER-P-5 AND DER-P-7 ALLERGENS OF THE HOUSE-DUST MITE DERMATOPHAGOIDES-PTERONYSSINUS

Der p 2, Der p 5 and Der p 7 are three allergens of the house-dust mit e Dermatophagoides pteronyssinus that have been cloned and expressed i n Escherichia coli as fusion proteins with glutathione-S-transferase ( GST). We showed that these recombinant allergens produced immediate hy persensitivity skin-test reactions in 70, 60 and 52% respectively of a group of mite-sensitive allergic patients who were strongly positive to whole mite extract (WME). Comparable positivities were found for se rum levels of specific IgE antibody against these allergens, as measur ed by the radioallergosorbant test (RAST). Overall, for the group of a llergic patients that we evaluated, the serum IgE antibody concentrati ons against Der p 2, 5 and 7 were calculated to represent about one th ird, one quarter and one fifth respectively of the levels measured aga inst the WME. However, for some patients the activity determined again st the separate allergens was far higher than that detected against th e WME, thus indicating that the concentration of these can be limiting in the WME. We found no significant correlations between the RAST lev els against Der p 2 and either Der p 5 or 7, and RAST-inhibition tests indicated a lack of cross-reactivity between Der p 2 and the other tw o allergens. In contrast, the RAST results revealed the existence of a significant immunological relationship between Der p 5 and 7. Althoug h a certain degree of reactivity against the GST fusion partner was fo und in the allergic patients studied, this was not a significant influ ence in determining the positivity against the recombinant allergens. These results confirm the in vivo biological activity of recombinant D er p 2, 5 and 7, and indicate that whilst Der p 2 is undoubtedly a maj or mite allergen, both Der p 5 and 7 make important contributions towa rd the overall allergenic activity of house-dust mites.