A new amplified monoclonal rat allergen assay used for evaluation of ventilation improvements in animal rooms.

Abstract

Available methods for the measurement of airborne laboratory animal allergens are not standardized and are often insufficiently sensitive for measurements in laboratories or in undisturbed animal rooms. Although low, the levels may be clinically relevant, because many scientists not involved in cleaning out cages or handling animals have rodent allergies. The purpose of this study was to develop a sensitive monoclonal assay to determine airborne rat allergen and test it in the evaluation of a sliding curtain system installed in refurbished rat rooms, with perforated, transparent polycarbonate screens, behind which were the cage racks. Monoclonal antibodies were produced against male rat urine by immunization in mice and fusion with mouse cell line Sp2/0. A novel biotinylated phenol compound was synthesized for immunoassay signal amplification in conjunction with horseradish peroxidase. Air filter samples were collected at a rate of 2 L/min, and allergen content in the filter eluates was determined. Two monoclonal antibodies were produced and used in a sandwich ELISA, which bound alpha2u-globulin (Rat n 1.02). The assay detection limit was 3.2 pg/ml, about tenfold increased sensitivity compared with the unamplified assay. Allergen levels were lower in rooms when curtains were closed (median, 0.2 ng/m3) than behind the curtains (0.9 ng/m3, p = 0.01) or if the curtains were open (0.9 ng/m3, p = 0.001). However, allergen levels during cage cleaning, when curtains were drawn apart, were high (18 ng/m3). We have developed a method for measurement of airborne rat allergen that can be standardized, measures an important allergen, and is sufficiently sensitive to measure low allergen levels with personal samplers.