An immunochemical method to measure atmospheric allergens.

Because particulate aeroallergens may exist in amorphous form as well as in pollen grains and fungal spores and because symptoms of allergic diseases presumably correlate with the total amount of allergen exposure, an immunochemical method of assay of aeroallergens would be useful. We report such a method based on (1) capture of airborne pollen, fungal spores, and amorphous particles 0.3 micrometer in diameter on fiberglass sheets with a high-volume air sampler; (2) elution of the sheets with buffered saline; and (3) analysis of eluate allergen content by radioallergosorbent test (RAST) inhibition assays. In preliminary indoor experiments we applied various quantities of short ragweed (SRW) pollen or dry Alternaria powder to the sheets while airflow was maintained at 1.19 m3/min. We compared techniques for extraction of allergen from the sheets, including homogenization, cutting and soaking, and descending elution of sheets. Although all three methods successfully extracted allergen from the sheets, an 8-hr descending elution procedure was optimal from the standpoint of yield and convenience. Eluates from filters exposed to as little as 4 mg of SRW pollen or Alternaria powder produced satisfactory RAST inhibition curves. When the sampler was operated outdoors continuously we could measure the atmospheric allergenic activity for both Alternaria and SRW from July to September. This allergenic activity was highly correlated with the traditional morphologic counts of airborne ragweed pollen and Alternaria spores.