Mugwort and sage (Artemisia) pollen cross-reactivity: ELISA inhibition and immunoblot evaluation.

BACKGROUND: Plants of the genus Artemisia are a source of fall allergic symptoms, particularly in the western United States. Studies have characterized the allergens in one of the major species (A. vulgaris) but currently there are no cross-reactivity data on the major United States species.
OBJECTIVE: The purpose of this study was to investigate the in vitro cross-reactivity among nine Artemisia species: A. frigida, A. annua, A. biennis, A. filifolia, A. tridentata, A. californica, A. gnaphalodes, A. ludoviciana, and A. vulgaris.
METHODS: The cross-reactivity was demonstrated with the use of enzyme-linked immunosorbent assay (ELISA) inhibitions and immunoblotting techniques utilizing a serum pool from patients allergic to Artemisia species.
RESULTS: The enzyme-linked immunosorbent assay inhibitions revealed strong cross-reactivity among all nine species with A. biennis and A. tridentata being two of the strongest inhibitors. The polyacrylamide gel electrophoresis showed a great deal of similarity in the bands among the nine species. The nitrocellulose blots showed similar IgE binding patterns among the Artemisia species with strong inhibition among all nine extracts.
CONCLUSIONS: These data all demonstrate very strong in vitro cross-reactivity among the nine Artemisia species studied. Such data have significant clinical relevance, suggesting that a single Artemisia species may be sufficient for allergy skin testing and formulation of immunotherapy extracts.