HIGHLY SENSITIVE AND SPECIFIC ELISA WITH MONOCLONAL-ANTIBODY CAPTURE TO MEASURE DERMATOPHAGOIDES-FARINAE 1-SPECIFIC IGE

Background: Dermatophagoides farinae (Der f) 1 is a major allergen in Der f extract. Measurement of Der f I-specific IgE has not been common ly used, because of the difficulty in obtaining large amounts of purif ied Der f 1. Objectives: To improve the diagnosis of dust mite allergy , we wanted to develop an ELISA to measure Der f 1-specific IgE in whi ch purified Der f 1 is not required. Methods: Using a monoclonal antib ody (mAb) against Der f 1, a mAb-capture ELISA was developed. Micropla tes coated with the mAb were sequentially incubated with crude Der f e xtract, serum samples, goat anti-human IgE, and conjugated rabbit anti -goat Igc. A conventional ELISA using purified Der f 1 as capture (Der f 1-ELISA) was developed to compare it with the mAb-capture ELISA. Re sults: There was a significant correlation between the two ELISAs (r = 0.89, P < .001) with a sensitivity of 0.8 U/mL. Both the assays were inhibited by the crude Der f extract in a dose-dependent manner. Using the two ELISAs, serum Der f 1-specific IgE was evaluated in 12 allerg ic patients with positive skin tests to Der f extract, 14 allergic pat ients with negative skin tests to Der f extract, and 15 healthy subjec ts. The mean Der f 1-IgE and the positivity rate of Der f I-IgE were h igher in the mite-allergic group and lower in the healthy group when t he mAb-ELISA was used (P < .01) than when the Der f 1-ELISA was used ( P < .05). Conclusions: Der f 1-specific IgE can be measured by mAb-cap ture ELISA using crude Der f extract. The mAb-ELISA is more sensitive and specific than the conventional Der f 1-capture ELISA in diagnosing dust mite allergy.