Binding of antibodies against birch pollen antigens/allergens to various parts of apples as studied by immuno-gold electron microscopy

Abstract

The clinically and biochemically observed correlation between birch pollen allergy and hypersensitivity to apples was investigated by immunocytochemical techniques. For this purpose, apple tissue was fixed in p-formaldehyde and embedded in Lowicryl K4M resin at -35 degrees C. Ultrathin sections were cut and successively incubated with rabbit antibodies against birch pollen antigens/allergens and protein A/gold. Specific antibody binding sites were detected throughout the apple fruit (peel, fruit flesh, seed). Control sections incubated with normal rabbit IgG antibodies and protein A/gold showed minimal background staining. It was concluded from the results of immunocytochemical labelling that apple tissue and birch pollen contain similar molecular structures which lead to the observed cross-reactions. The present immunocytochemical results confirm biochemical investigations reporting partial structural identity of antigens/allergens in birch and apple.