Characterization of the house dust mite allergen Der p 7 by monoclonal antibodies

The house dust mite allergen Der p 7, which was defined by cDNA cloning, has been shown to react with about 50% of allergic sera and corresponds to or is antigenically related to at least three different sized components in mite extracts. To characterize these entities, monoclonal antibodies (MoAbs) were generated by immunizing BALB/c mice affinity-purified Der p 7-GST (glutathione S-transferase) fusion protein. MoAbs WH9 and WH22 showed positive reactivity to recombinant Der p 7 negative reactivity to GST and the Der p 5-GST fusion protein in ELISA and immunoblotting. The specificity of both MoAbs was confirmed by inhibition of the ELISA activity by recombinant Der p 7 but not by the recombinant Der p 5. Immunoblot analysis demonstrated that both MoAbs showed reactivities to components with molecular weights (mol. wt.) of 31, 30 and 26 kDa reactive to both MoAbs. At least six major forms with different pI or size were indicated by 2-D gel analysis. In addition to characterization of Der p 7, both MoAbs may also be considered for use in the standardization of Der p 7 in mite extracts.