Immunogold electron microscopic localization of the 2 EF-hand calcium-binding pollen allergen Phl p 7 and its homologues in pollens of grasses, weeds and trees.
BACKGROUND
The 2 EF-hand calcium-binding allergen from timothy grass pollen, Phl p 7, contains the majority of relevant IgE epitopes among calcium-binding allergens occurring in pollen species of different plants.


OBJECTIVE
To describe the ultrastructural localization of Phl p 7 allergen in timothy grass pollen and its homologues in a broad spectrum of allergologically relevant pollens from grasses (timothy grass, rye grass), trees (birch, alder, olive) and weeds (mugwort, ribwort, ragweed) commonly growing in Europe.


METHODS
Mature pollens from 8 different plant species were collected and anhydrously prepared for transmission electron microscopy. In ultrathin sections, allergens were localized using an antibody prepared against a Phl p 7-derived peptide comprising the C-terminal half of the Phl p 7 wild-type molecule in combination with a secondary antibody coupled to 10-nm colloidal gold particles.


RESULTS
Phl p 7 and Phl p 7 homologues were detected in pollen from each of the 8 pollen species investigated. The allergens were found in the cytoplasm of the pollen grains (cytoplasmic matrix, mitochondria, nuclei) and in the pollen wall (preferably the exine). Reserve materials were unlabeled.


CONCLUSIONS
The 2 EF-hand calcium-binding allergen Phl p 7 from timothy grass and its homologues can be localized in all pollen species under investigation. This finding confirms that Phl p 7 is a marker allergen for sensitization of patients to a novel family of 2 EF-hand calcium-binding pollen allergens occurring in a number of important allergenic plants in Europe.
Grote
Monika
M
Institute of Medical Physics and Biophysics, University of Münster, Münster, Germany. mgrote@uni-muenster.de
Westritschnig
Kerstin
K
Valenta
Rudolf
R
D000485:Allergens / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D000906:Antibodies / Q000502:physiology; D052179:Antigens, Plant; D019659:Asteraceae / Q000276:immunology* / Q000648:ultrastructure; D002135:Calcium-Binding Proteins / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D020832:EF Hand Motifs / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D031784:Phleum / Q000276:immunology* / Q000648:ultrastructure; D011058:Pollen / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding / Q000276:immunology; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D014197:Trees / Q000276:immunology* / Q000648:ultrastructure
D000485:Allergens; D000906:Antibodies; D052179:Antigens, Plant; D002135:Calcium-Binding Proteins; C468525:Phl p 7 allergen