A new method for simultaneous immunodetection and morphologic identification of individual sources of pollen allergens

Abstract

Background: Exposure to outdoor allergens has commonly been estimated by collecting airborne particles with a Hirst-type spore trap and then using morphologic criteria to identify the intact pollen grains and fungal spores that are recognized as allergen sources. Several antibody-based blotting or fixation methods have also been developed that enable the counting of amorphous airborne particles carrying allergen, but none of these methods allow the ready association of the released allergen with the morphologically identifiable particle of origin. A method has been developed that uses pressure-sensitive adhesive tape to sample the airborne particles and then allows the immunoidentification of the specific particles that are the allergen sources. Objective: Our purpose was to visualize and immunostain the particles carrying pollen allergen that are collected with a volumetric spore trap. Methods: A Burkard sampler was used to collect airborne particles onto pressure-sensitive adhesive tapes. The particles were permanently fixed between the tape and a protein-binding membrane when the tape was laminated with the membrane. Allergens that elute from the particles onto the membrane were detected with a range of antibodies. Both the particle and associated immunostained allergen were viewed through the transparent tape for final microscopic identification. Results: Polyclonal and monoclonal antibodies and IgE from allergic patients stained allergens in the periphery of particles collected on the tapes. Individual pollen grains and paucimicronic particles were seen with halos of immunostained allergen surrounding them. When IgE was used, the density of immunostaining in the halo surrounding Lolium perenne pollen grains was found to be proportional to the level of Lolium -specific IgE. The method is highly sensitive and can be used to detect different airborne particles that carry allergen. Both the particle and the immunostaining can be subjected to a range of simple measurement techniques. Conclusion: Individual particles carrying allergens and antigens were visualized. These particles included intact pollen grains, paucimicronic particles, and fungal spores. (J Allergy Clin Immunol 2000;105:725-31.)