Allergic contact dermatitis to costus: removal of haptens with polymers.

Costus oil, an iol isolated from a Composite, Saussurea lappa C., used in perfumery, is responsible of numerous cases of allergic contact dermatitis (ACD). The haptens incriminated are sesquiterpene lactones, costunolide and dehydrocostuslactone. These lactones can be removed from the oil by using a polymer, aminoethyl-polystyrene, to which they become bound: the passing solution is lactone-free. A group of guinea-pigs could be successfully sensitized (Freund Complete Adjuvant Test) to costus essential oil, while another group, injected in the same way with polymer-treated essential oil (i.e. lactones) could not be sensitized. This polymer therefore provides a means to render complex plant extracts non-allergic.