Immunoquantitative Measurement of Soybean Aeroallergen Emissions

Environmental allergen exposure plays an important role in the development and expression of asthma and allergy. To study allergen exposure, it is necessary to actually measure allergen levels. Direct measurement is also needed to assess what levels lead to sensitisation or provoke symptoms in already sensitised subjects, and evaluate the efficacy of allergy reduction strategies (1). The measurement of aeroallergens plays a key role in asthma prevention. Both the epidemiological studies and the studies on specific IgE to soybean carried out following the asthma epidemics in Barcelona attributed their cause to the unloading of soybean in the harbour (2-3). The environmental intervention in September 1987 with the installation of bag filters in a silo led to a decrease in airborne soybean concentrations and the subsequent disappearance of the epidemics (4). The 1,555 U/m3 level of soybean allergen detected during a determined asthma epidemic day (5-6) was substantially higher than the highest value (165 U/m3) recorded in 22 unloading days after the interventions (4). These data show that the measurement of soybean aeroallergen levels in harbours loading and unloading soybean is of increasing importance in controlling the efficiency of the environmental interventions in order to prevent new asthma outbreaks in these areas. In the evaluation of occupational asthma, measurement of the causal agent in the air at worksites is a necessary additional link in the chain of evidence that a suspected allergen is the cause of the pathology. Such measurements are particularly useful when the allergen is unknown, the environment of interest has never before been assessed, and control measures have to be considered. Knowledge of the concentration at work also allows correlation between exposure of workers and an inhalation challenge test in the laboratory, which is performed in individual patients to confirm that the suspected allergenic material that evoked the IgE antibody can actually cause an asthmatic response (7). Thus, it is of great interest to monitor soybean dust levels indoors.