Allergen carriage by atmospheric aerosol. II. Ragweed-pollen determinants in submicronic atmospheric fractions.

Outdoor air was drawn by a vacuum system through a 0.8 micron molecular membrane filter and a back-up, refrigerated condensor from 8 A.M. to 5 P.M. daily during the 1982 ragweed-pollen season. Sample sets from each day were collected and stored separately. Condensate was collected in a freezing jacket, thawed, refiltered through a 0.45 micron filter, and lyophilized. Reconstituted condensates evoked wheal-and-flare skin reactions in a ragweed-sensitive individual and produced significant inhibition in an IgG-ELISA system by use of ragweed-pollen protein or ragweed antigen E conjugated to polystyrene microtiter plates, pooled serum of patients on ragweed immunotherapy, and alkaline phosphatase-labeled anti-human IgG. Earlier, in 1983 in this JOURNAL, we reported the presence of airborne ragweed-pollen antigen in aerosol fractions below 5 micron. The present data demonstrate similar in filtrates well below the micronic range. Furthermore, these antigenic properties are substantially associated with atmospheric water vapor-either naturally or as a readily-induced result of the collection procedure. These results suggest that naturally occurring mists, although free of native particulates, may yet carry allergens of clinical significance.