Identification of common allergenic structures in mugwort and ragweed pollen.
Identification of common allergenic structures in mugwort and ragweed pollen.


BACKGROUND
Despite the rare occurrence of ragweed in Middle Europe, a surprisingly high number of patients allergic to mugwort, a frequently encountered weed, display IgE reactivity against ragweed pollen allergens.


OBJECTIVE
The aim of this study was to investigate whether the high prevalence of IgE reactivity against ragweed in patients allergic to mugwort is caused by the presence of common allergenic determinants. We also sought to characterize any cross-reactive allergens.


METHODS
Common allergenic structures in mugwort and ragweed pollen were characterized by qualitative IgE immunoblot inhibition experiments performed with natural allergen extracts and recombinant allergens. The degree of cross-reactivity was estimated by quantitative CAP-FEIA competitions. The clinical significance of cross-reactive IgE antibodies was studied with histamine release experiments and nasal provocation tests.


RESULTS
Mugwort and ragweed RAST values were significantly correlated in a population of 82 Austrian patients allergic to mugwort. IgE antibodies cross-reacted with allergens of comparable molecular weight that were present in both extracts. By using recombinant birch profilin and specific antisera for IgE inhibition experiments, profilin was identified as one of the cross-reactive components in mugwort and ragweed pollen. Preincubation of sera from patients allergic to mugwort with mugwort extract inhibited IgE binding to ragweed pollen extract greater than 80%. Mugwort and ragweed pollen extract induced comparable histamine release and reduction of nasal air flow in a patient with IgE reactivity against the major mugwort allergen Art v 1.


CONCLUSIONS
In addition to profilin, mugwort and ragweed pollen contain a number of cross-reactive allergens, among them the major mugwort allergen Art v 1. Cross-reactive IgE antibodies can lead to clinically significant allergic reactions.
Hirschwehr
R
R
Institute of General and Experimental Pathology, AKH, University of Vienna, Austria.
Heppner
C
C
Spitzauer
S
S
Sperr
W R
WR
Valent
P
P
Berger
U
U
Horak
F
F
Jäger
S
S
Kraft
D
D
Valenta
R
R
D000485:Allergens / Q000032:analysis / Q000737:chemistry* / Q000276:immunology*; D019306:Artemisia / Q000737:chemistry / Q000276:immunology*; D003285:Contractile Proteins; D003429:Cross Reactions; D000939:Epitopes / Q000276:immunology; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology*; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology*; D008840:Microfilament Proteins / Q000032:analysis / Q000276:immunology; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry* / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology; D010944:Plants / Q000276:immunology; D010946:Plants, Medicinal; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D051304:Profilins
D000485:Allergens; D003285:Contractile Proteins; D000939:Epitopes; D008840:Microfilament Proteins; D010936:Plant Extracts; D010940:Plant Proteins; D051304:Profilins; D007073:Immunoglobulin E