Oxidative TryptophanModification by Terpene- andSqualene-Hydroperoxides and a Possible Link to Cross-Reactions inDiagnostic Tests.

Hydroperoxides can act as specifichaptens and oxidatively modifyproteins. Terpene hydroperoxides trigger unusually high frequenciesof positive skin reactions in human patients if tested at high concentrations.It is unknown whether this is due to specific hapten formation. Here,we show that both terpene hydroperoxides and the endogenous hydroperoxideformed from squalene can oxidatively modify tryptophan. Oxidativemodifications of Trp were recently postulated to explain cross-sensitizationbetween unrelated photosensitizers. Current observations may extendthis hypothesis: Oxidative events triggered by endogenous hydroperoxidesand hydroperoxides/oxidants derived from xenobiotics might lead toa sensitized state detected by patch tests with high concentrationsof hydroperoxides. [ABSTRACT FROM AUTHOR]