PROPERTIES OF TREE AND GRASS-POLLEN ALLERGENS - REINVESTIGATION OF THE LINKAGE BETWEEN SOLUBILITY AND ALLERGENICITY

In this study we reinvestigated the kinetics of allergen release from birch pollen (Betula verrucosa) and timothy grass pollen (Phleum prate nse) using different protein extraction procedures, immunoblotting wit h specific antibodies and immune electron microscopy. Pollen allergens such as the major birch pollen allergen, Bet v I, the major timothy g rass pollen allergens, Phl p I and Phl p V, group-II/III allergens fro m timothy grass and profilins were released rapidly and in large amoun ts from hydrated pollen. Within a few minutes pollen allergens could b e detected in aqueous supernatants prepared from birch and grass polle n with serum IgE or specific antibodies. In parallel the allergen cont ent in the pollen pellet fractions decreased. A nonallergenic protein such as heat shock protein 70 can be extracted in sufficient amounts o nly with harsh extraction procedures. Immune electron microscopy of dr y and rehydrated birch pollens showed that after short hydration, the major birch pollen allergen, Bet v I, migrated into the exine and to t he surface of intact pollen grains, whereas profilin, against which a lower percentage of patients is sensitized, was retained in the pollen grain. Comparing the amino acid composition and hydrophilicity of the tested allergens with a nonallergenic protein such as heat shock prot ein 70, no significant difference was noted. In agreement with earlier observations we conclude that the allergenic properties of proteins a re rather linked to the amount and speed of solubility from airborne p articles than to intrinsic properties.