SummaryPatients with Compositae sensitization are routinely warned against the ingestion of vegetables, spices, teas and herbal remedies from this family of plants. The evidence for the occurrence of systemic allergic dermatitis caused by sesquiterpene lactone-containing plants is mostly anecdotal and based on statements from patients rather than scientific data. However, a few clinical reports on accidental sensitization and exposure and oral challenge prove the existence of this kind of reaction, most convincingly for strong contact allergens such as costunolide in bay leaves, and less so for weak allergens such as those of lettuce. Other Compositae species suspected of causing systemic reactions are artichoke, mugwort, yarrow, dandelion, feverfew, and elecampane. Some Compositae vegetables and teas, such as lettuce and chamomile tea, may induce systemic reactions through both humoral and cell-mediated mechanisms. It is difficult to disentangle the contribution of these reactions to both local and systemic symptoms of skin and mucous membranes in, for example, lettuce contact allergy. Further studies are needed to assess the prevalence of systemic allergic dermatitis caused by sesquiterpene lactones, and to clarify the pathogenesis for individual haptens.Key words: Asteraceae; challenge; Compositae; herbal tea; Lactuca sativa; Laurus nobilis; sesquiterpene lactones; systemic allergic dermatitis.Sesquiterpene lactones (SLs) constitute one of the largest groups of secondary plant metabolites, with > 5000 compounds (1, 2). They are reactive low molecular weight substances with antimicrobial, antifeedant, growth-modifying and allelopathic properties in general, and are thus important for plant survival (2). SLs occur in at least 17 plant families, but most abundantly in the sunflower family (Asteraceae or Compositae), where they are important taxonomic markers (3). The ability of SLs to bind covalently with biological macromolecules is also the basis of their allergenicity, and the reason why the sunflower family contains so many sensitizing species (1, 4).Contact sensitization to allergenic SLs may imply contact allergy to plants that are consumed either as vegetables, spices, teas, or herbal remedies. This may cause systemic allergic contact dermatitis, which is most frequently reported to be caused by metals, drugs, and plants/herbals (5-9). However, reports on Compositae-related systemic allergic dermatitis are often anecdotal (10-13).In contrast to immediate-type hypersensitivity reactions, which may be detected by serological and laboratory tests in addition to clinical tests, the diagnosis of systemic allergic dermatitis is based on clinical symptoms and signs, and possibly oral or other suitable challenges.The aim of this article is to review the evidence for the occurrence of systemic allergic contact dermatitis caused by Compositae and other SL-containing plants.
MethodsThe older literature was searched via textbooks and references from both old and new articles. The newer literature was searched via the...