Characterization of peptidic and carbohydrate cross-reactive determinants in pollen polysensitization.
BACKGROUND
Cross-reactivity may be due to protein sequence or domain homologies and/or the existence of cross-reactive carbohydrate determinants (CCDs). The clinical relevance of peptidic cross-reactivities is well known, whereas that of CCDs is still a question of debate. The aim of this study is to characterize the IgE specificity of various patients suffering from pollen polysensitization to identify both peptidic and carbohydrate cross-reactive determinants.


METHODS
Rapeseed, grass and Arabidopsis proteins were separated by isoelectric focusing, followed by SDS-PAGE, and transferred to a nitrocellulose sheet. The sheets were incubated either with an individual serum from a birch+grass-sensitive patient, followed by anti-human IgE, or with labelled Concanavalin A (ConA). Binding inhibition was tested by incubation of the sera with a mixture of sugar residues.


RESULTS
The results showed two different patterns of cross-reacting sera: a pattern that implies few proteins, not always glycosylated and known as allergens, and a pattern that implies numerous proteins with molecular masses over 30 kDa. This second pattern was very close to the ConA -binding pattern. The IgE binding was abolished by pre-incubation with sugar residues only in the case of the second pattern.


CONCLUSIONS
This study shows that multiple pollen sensitizations could result from multiple sensitizations to specific proteins or from a cross-sensitization to a wide range of glycoproteins. Two-D blots allow to characterize a cross-sensitization due to carbohydrate determinants, and thus to improve the diagnosis of allergy and its medical treatment.
Chardin
H
H
Université Paris Descartes, Paris, France. helene.chardin@espci.fr
Sénéchal
H
H
Wal
J M
JM
Desvaux
F X
FX
Godfrin
D
D
Peltre
G
G
D000485:Allergens / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D017360:Arabidopsis / Q000737:chemistry; D015153:Blotting, Western; D029688:Brassica napus / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D003429:Cross Reactions / Q000276:immunology; D031745:Dactylis / Q000737:chemistry; D015180:Electrophoresis, Gel, Two-Dimensional; D000939:Epitopes / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood / Q000737:chemistry; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D011058:Pollen / Q000737:chemistry / Q000276:immunology*
D000485:Allergens; D002241:Carbohydrates; D000939:Epitopes; D010455:Peptides; D010936:Plant Extracts; D007073:Immunoglobulin E