Sensitization and cross-reaction patterns in Danish Compositae-allergic patients

Results of aimed patch testing with constituents of sesquiterpene lactone (SL) mix, Compositae mix (CM) and other Compositae extracts and allergens in 190 Compositae-allergic patients detected in an 8-year period are presented. Feverfew of CM elicited positive reactions most frequently, followed by tansy, wild chamomile, yarrow and arnica, whereas dehydrocostus lactone of SL was the most frequent elicitor of positive reactions, followed by alantolactone and costunolide. Chrysanthemum (Dendranthema) and marguerite (Argyranthemum frutescens) were the most important suspected sensitizers in both occupationally and nonoccupationally exposed, and cross-reactions between chrysanthemum and feverfew/tansy/chamomile may partly explain the high prevalence of positive reactions to the 3 last mentioned. In the nonoccupationally sensitized group, garden plants such as feverfew, blanket flower (Gaillardia), elecampane (Inula helenium), large yellow ox-eye (Telekia speciosa) and cosmea (Cosmos) were additional important allergenic plants. The 3 last mentioned were picked up by SL mix. Most of the lettuce-sensitized persons were CM-positive. 19% of the occupationally sensitized group were negative to both SL and CM, making very aimed patch testing necessary, notably when suspecting rare sensitizers such as Gerbera and star of the veldt (Osteospermum). The significance of the weeds dandelion, dog fennel and ox-eye daisy as sensitizers is not clarified, but they are probably less important than cultivated plants.