Allergic contact dermatitis from sesquiterpenoids of the Compositae family of plants

The sesquiterpene lactone mix: A review of past, present and future aspects

The sesquiterpene lactones (SLs) are secondary plant metabolites, which are widespread in the Compositae/Asteraceae plant family. The first SLs were detected more than 100 years ago, and allergic contact dermatitis from Compositae has been reported since the beginning of the 1900s, but it was not until the late 1960s and early 1970s that a collaboration between dermatologists, chemists and botanists led to the detection of SLs as the main allergens of Compositae plants. In the 1980s, the SL mix, consisting of equimolar amounts of alantolactone, costunolide and dehydrocostus lactone, was developed as a screening agent for Compositae sensitisation. Today, after inclusion of SL mix in the baseline series, the mean prevalence of reactions in Europe is around 1%, and in North America 0.8%. In countries outside Europe and North America, the prevalence ranges between 0% and 10.7%. The detection rate of SL mix is lower than that of some plant extracts, and ideally, SL mix should be supplemented with a mix of SLs from locally prevalent allergenic plants. The prevalence of positive reactions to SL mix suggests continued baseline testing in most European countries, North America, New Zealand, Australia and probably some Chinese centres.

Research Advances on Health Effects of Edible Artemisia Species and Some Sesquiterpene Lactones Constituents

The genus Artemisia, often known collectively as "wormwood", has aroused great interest in the scientific community, pharmaceutical and food industries, generating many studies on the most varied aspects of these plants. In this review, the most recent evidence on health effects of edible Artemisia species and some of its constituents are presented and discussed, based on studies published until 2020, available in the Scopus, Web of Sciences and PubMed databases, related to food applications, nutritional and sesquiterpene lactones composition, and their therapeutic effects supported by in vivo and clinical studies. The analysis of more than 300 selected articles highlights the beneficial effect on health and the high clinical relevance of several Artemisia species besides some sesquiterpene lactones constituents and their derivatives. From an integrated perspective, as it includes therapeutic and nutritional properties, without ignoring some adverse effects described in the literature, this review shows the great potential of Artemisia plants and some of their constituents as dietary supplements, functional foods and as the source of new, more efficient, and safe medicines. Despite all the benefits demonstrated, some gaps need to be filled, mainly related to the use of raw Artemisia extracts, such as its standardization and clinical trials on adverse effects and its health care efficacy.

Effects of diet on skin sensitization by nickel, poison ivy, and sesquiterpene lactones

Skin contact or exposure to sensitizers often occurs as a consequence of occupational exposures (e.g. poison ivy in forestry), wearing jewelry (e.g. nickel), or use of cosmetics (e.g. fragrances). However, many of the known skin sensitizers or their chemical variants are also consumed orally through foods or other sources. Since oral exposure to antigenic substances can lead to tolerance, consumption of sensitizers may impact the development and potency of skin sensitization, especially if the sensitizer is consumed early in life, prior to the first skin contact. To address this issue, we have reviewed human clinical and epidemiological literature relevant to this subject and evaluated whether early oral exposures to relevant sensitizers, or their chemical variants, are associated with reduced prevalence of skin sensitization to three main allergic sensitizers - nickel, urushiols of poison ivy, and sesquiterpene lactones of chrysanthemum and other plants.

Ragweeds and relatives: Molecular phylogenetics of Ambrosiinae (Asteraceae)

Ambrosiinae are one of the most distinct subtribes in the Heliantheae alliance (Asteraceae), mainly due to specialization toward wind pollination. Taxa of the subtribe are principally native to the Americas, although some species have attained a cosmopolitan distribution. Members of subtribe Engelmanniinae are considered close to Ambrosiinae, due to shared morphological traits. However, the placement of Ambrosiinae within the Heliantheae alliance has not yet been corroborated by phylogenetic analyses. In the present study, we test the circumscription of subtribe Ambrosiinae and examine relationships among its genera. We used sequence information from three plastid (psbA-trnH, trnQ-rps16 and trnL-F) and two nuclear (ITS and D35) marker regions. Phylogenetic inference analyses were conducted, applying Bayesian Inference (BI) and Maximum Likelihood (ML). Subtribe Ambrosiinae is found monophyletic or nearly so in all analyses. The genera Dugesia and Rojasianthe (previously considered part of subtribe Engelmanniinae) in some cases cluster together with Ambrosiinae; these genera are clearly not part of Engelmanniinae. Within Ambrosiinae, the genera Parthenium and Parthenice occupy basal positions, whereas members of the genus Ambrosia are the most derived representatives of the subtribe. Previous subdivision of Ambrosiinae into "Iveae" (members having androgynous capitula and free achenes) and "Ambrosieae" (genera with unisexual heads and achenes enclosed in burs) is not corroborated. Results also allow consideration of relationships among species and subgeneric groups within Parthenium, Iva, and Ambrosia.

Emerging Anti-Mitotic Activities and Other Bioactivities of Sesquiterpene Compounds upon Human Cells

We review the bio-activities of natural product sesquiterpenes and present the first description of their effects upon mitosis. This type of biological effect upon cells is unexpected because sesquiterpenes are believed to inactivate proteins through Michael-type additions that cause non-specific cytotoxicity. Yet, certain types of sesquiterpenes can arrest cells in mitosis as measured by cell biology, biochemical and imaging techniques. We have listed the sesquiterpenes that arrest cells in mitosis and analyzed the biological data that support those observations. In view of the biochemical complexity of mitosis, we propose that a subset of sesquiterpenes have a unique chemical structure that can target a precise protein(s) required for mitosis. Since the process of mitotic arrest precedes that of cell death, it is possible that some sesquiterpenes that are currently classified as cytotoxic might also induce a mitotic arrest. Our analysis provides a new perspective of sesquiterpene chemical biology.

Allergenic sesquiterpene lactones from cushion bush (Leucophyta brownii Cass.): new and old sensitizers in a shrub-turned-a-pot plant

BACKGROUND

The Australian cushion bush (Leucophyta brownii) of the Compositae family of plants has become a popular pot and container plant. The plant produces the sesquiterpene lactone allergen calocephalin.

OBJECTIVES

To assess the sensitizing potential of sesquiterpene lactones from cushion bush.

PATIENTS/MATERIALS/METHODS

Eleven Compositae-sensitive patients were patch tested with seven sesquiterpene lactones isolated from cushion bush.

RESULTS

Six of seven sesquiterpene lactones elicited positive reactions in 4 of 11 patients.

CONCLUSIONS

The well-known sesquiterpene lactone pseudoivalin and its derivative pseudoivalin acetate, as well as calocephalin and tomentosin, were confirmed to be sensitizers, whereas leucophytalin A and 4α-hydroxy-5αH,10αH-1,11(13)-guaidien-8β,12-olide were shown to be allergenic for the first time. The patch test reaction patterns seem to follow the chemical patterns, which may eventually make it possible to trace primary sensitizers and advise patients more precisely.

Allergic contact dermatitis to plants: understanding the chemistry will help our diagnostic approach

Allergic contact dermatitis due to plants is common. Potentially allergenic plants and plant products are found in many everyday environments, such as the home, the garden, the workplace, and recreational settings. By improving our knowledge of allergenic plant-derived chemical compounds, we will be better positioned to identify novel allergens. We review the most relevant chemical allergens that contribute to plant allergic contact dermatitis and propose a clinical classification system based on 5 major families of chemical sensitizers: α-methylene-γ-butyrolactones, quinones, phenol derivatives, terpenes, and miscellaneous structures (disulfides, isothiocyanates, and polyacetylenic derivates). We also describe the different clinical pictures of plant allergic contact dermatitis and review currently available patch test materials. A better understanding of the specific allergens involved in plant allergic contact dermatitis will help to predict cross-reactivity between different plant species or families.

Alpha-methylene-gamma-butyrolactones: versatile skin bioactive natural products

Natural products containing an alpha-methylene-gamma-butyrolactone moiety, mainly of the sesquiterpene type, are widely observed in plants, which upon coming into contact with skin, will induce major skin toxicological side effects or phytodermatitis. Indeed two main dermatological pathologies have been associated with a skin exposure to molecules containing an alpha-methylene-gamma-butyrolactone moiety: allergic contact dermatitis (ACD) and chronic actinic dermatitis (CAD). ACD is an immunologically based disease resulting from modifications of epidermal proteins by sensitizers or haptens. Indeed, alpha-methylene-gamma-butyrolactones are highly electrophilic structures that can act as Michael acceptors towards nucleophilic residues of proteins. Cysteine and lysine are the most modified residues leading, in the case of enantiomerically pure lactones, to the formation of diastereomeric adducts. This chemical enantioselectivity induces an enantiospecificity of the allergic reaction, i.e., an individual sensitized to one enantiomer will not develop clinical symptoms when exposed to the other enantiomer and vice versa. Sesquiterpene lactones have been also associated with another pathology that involves UV irradiation and DNA modifications. Interestingly, it was found that alpha-methylene-gamma-butyrolactones, in addition to their electrophilic properties, were highly photoreactive molecules able to react with thymine/thymidine to form [2 + 2] photoadducts in very high yields. In all cases a syn regioselectivity was observed, probably associated with the polarization of the exomethylenic bond. This high photoreactivity of alpha-methylene-gamma-butyrolactones towards thymidine could be an explanation of the progressive evolution of allergic contact dermatitis towards chronic actinic dermatitis.

Clinical patterns of phytodermatitis

Exposure to plants is very common, through leisure or professional activity. In addition, plant products and botanic extracts are increasingly present in the environment. Cutaneous adverse reactions to plants and their derivatives occur fairly frequently, and establishing the correct diagnosis is not always easy. The astute clinician relies on a detailed history and a careful skin examination to substantiate his opinion. This article reviews the characteristic clinical patterns of phyto- and phytophotodermatitis and some less common presentations.

Pyrethrum Allergic Contact Dermatitis in Humans—Real?, Common?, or Not Documented?: An Evidence-Based Approach

Pyrethrum has been reported to produce allergic contact dermatitis in humans. Moreover, it has been speculated that cross reactions occur in ragweed-sensitized people. This review presents the botany, contemporary chemistry, and case reports of alleged allergic contact dermatitis. Our interpretation suggests that the evidence presented in literature does not show that allergic contact dermatitis results from exposure to pyrethrum. Similarly, the data do not suggest cross reactions in ragweed-sensitized people. Changes in the chemical composition of the refined pyrethrins suggest the putative sensitizer is present at a lower level in today's refined extracts than in ground pyrethrum flowers or the extracts used earlier.

Contact allergy to herbal teas derived from Asteraceae plants

Contact allergy to herbal teas derived from the Asteraceae plant family was investigated in patients allergic to sesquiterpene lactones (SLs). 20 patients with a known contact allergy to SLs were recalled and patch tested with aqueous extracts of 8 different herbal teas based on Asteraceae plants as well as with parthenolide and other SLs. In 18 of 20 patients with SL allergy, there were positive test reactions to the Asteraceae teas, mainly to those based on German chamomile, dandelion and wormwood. Among the SLs, parthenolide was the most frequent co-reactor. Obviously, most patients with a contact allergy to SLs are allergic to commercial teas derived from the Asteraceae plant family as well.

Airborne contact dermatitis from Ambrosia deltoidea (triangle-leaf bursage)

3 cases of contact dermatitis due to exposure to airborne allergens from Ambrosia deltoidea (triangle-leaf bursage) are presented. Although airborne plant dermatitis was suggested in each case by a history of aggravation of the rash by outdoor exposure and typical skin lesions, patch testing with an oleoresinous extract of A. deltoidea leaves identified the source of the sensitizer, not previously reported. As A. deltoidea is a ragweed that probably contains sesquiterpene lactones nearly identical to those of ragweeds widely prevalent in most of North America, the patients presented indicate the need for commercially available, standardized, plant extracts for patch testing in this country. The finding of positive patch tests with filters from an air sampler placed in 1 patient's domestic environment suggests a new avenue of investigation in airborne contact dermatitis.

[Compositae dermatitis]

INTRODUCTION

Compositae dermatitis is an allergic contact dermatitis caused by plant species of the Compositae family. The first report of a cutaneous reaction to the Chrysanthemum genus was made by Howe JS in 1887. In 1895 Maiden JH reported about skin lesions among men working with Tagetes minuta. Case reports of contact allergic-ragweed dermatitis appeared in the American literature as early as 1919. The North American feverfew--Parthenium Hysterophorus was brought to India from America in 1956 and it caused thousands of cases of so-called parthenium dermatitis. Ragweed and parthenium dermatitis became prototypes for the classic, so-called "airborne" Compositae dermatitis, that affects primarily exposed skin surfaces, and produces a universal erythroderma.

EPIDEMIOLOGY

The frequency of contact allergy to Compositae in Europe is higher than previously believed. It occurs most frequently in middle-aged and elderly persons, but also in all age groups. During the two past decades a more equal sex ratio has been established. The prevalence varies from 0.7-1.4% in the general population, up to 4.5% among occupationally exposed persons. Compositae allergy is among the top ten contact sensitivities in Europe. In North Europe plants were the cause of 4.4% cases of occupational allergic contact dermatitis. ETIOLOGY AND PATHOGENESIS: Among cultivated Compositae plants, Chrysanthemum is considered to be a major sensitizer in Europe (60%). Among the edible types, it is lettuce--Lactuca sativa and endive Cichorium endivia (20-30%), and wild-growing feverfew--Tanace--tum parthenium (70-90%), tansy--Tanacetum vulgare (54%), and dandelion--Taraxacum officinale (65%). Sesquiterpene lactones are the main sensitizers of the Compositae family. Other components, thiophenes and acetylenes are said to elicit only phytophotodermatitis, but recent studies have demonstrated that some thiophenes and benzofuran derivates possess not only phototoxic activity, but also sensitizing properties. Photosensitivity is present in 22-75% Compositae sensitive individuals. Extracts from Compositae are known to be phototoxic in vitro. Photoreactivity of alpha-methylene-gamma-la-ctone group of sesquiterpene-lactone directed towards the DNA base thymine, thus producing intermolecular 2 + 2 photoadducts (antigen within the cell), was also thought to be related to photosensitivity. Clinical manifestations vary from generalized eczema (20-30%), eczema of hands and face (24%), hand (36-44%), or facial eczema (11-28%). 65% of patients have vesicular hand eczema.

DIAGNOSIS

Routine patch testing with sesquiterpene lactone mix, aimed testing with Compositae extracts screening mix, Compositae plants, and with their extracts, whereas the treatment of choice is a specific allergen-immunotherapy.

Contact allergy to the Asteraceae plant Ambrosia artemisiifolia L (ragweed) in sesquiterpene lactone-sensitive patients in southern Sweden

Ambrosia artemisiifolia L. a classical cause of ragweed dermatitis in North America, is also found in Europe. 17 patients with contact allergy to sesquiterpene lactone (SL) mix were recalled for patch testing with extracts of North American and Swedish ragweed, the latter harvested in summer and autumn. 8/17 patients were test-positive to the American extract, 14/17 to the Swedish summer extract and 15/17 to the autumn extract. All patients except 1 were found to have a chronic hand eczema of the pompholyx type. 5/16 hand eczema patients had a flare-up of their pompholyx at patch testing. We concluded that patients with SL mix allergy are allergic to American as well as to Swedish ragweed. Pompholyx seems to be a frequent clinical picture in patients with SL mix allergy.

Occupational contact dermatitis. Recognition and management

Occupational contact dermatitis (OCD) represents 90 to 95% of all occupational dermatoses. The incidence rate of OCD is estimated to be around 0.5 to 1.9 cases per full-time worker per year. However, epidemiologic data are lacking and incidence is probably underestimated, especially in the US. Over the past 20 years, OCD has been the most frequently reported occupational disorder to German social insurance institutions. Critical factors in the management of OCD are recognition of clinical features, knowledge of allergens and irritants present in different occupational fields, knowledge of suitable protection, interpretation of patch test results, and awareness of medicolegal aspects. Management of OCD should be carried out by dermatologists and patch test clinics in cooperation with physicians specialized in industrial medicine. Individuals at high risk of OCD are hairdressers, dental laboratory technicians, other healthcare workers, construction industry workers, metal workers, leather and shoe manufacturers, florists and gardeners, and bakers, caterers, confectioners and cooks.

The seamy side of natural medicines: contact sensitization to arnica (Arnica montana L.) and marigold (Calendula officinalis L.)

Medical remedies of plant origin have gained increasing popularity in recent years. Both anaphylactic and eczematous allergic reactions are on the rise, accordingly. Arnica and marigold, both of the Compositae family, are in widespread use, but only limited data are available on their allergenic potential. We tested 443 consecutive patients, in addition to the European standard and other series, with Compositae mix, sesquiterpene lactone mix, arnica, marigold, and propolis. 5 subjects ( approximately 1.13%) reacted to arnica, 9 ( approximately 2.03%) to marigold. The Compositae mix was positive in 18 cases ( approximately 4.06%). Among them were 3 out of 5 individuals with a sensitization to arnica, and 4 out of 9 who reacted to marigold. Sensitization to arnica and marigold was often accompanied by reactions to nickel, Myroxylon Pereirae resin, fragrance mix, propolis, and colophonium. We conclude that Compositae allergy contributes significantly to the epidemiology of contact dermatitis and that sensitization to arnica and marigold cannot be assessed by testing with the Compositae or sesquiterpene mix alone. As extracts of these plants are frequently used in occupational and cosmetic products, patch testing with additional plant extracts or adjustment of the commercial Compositae mix to regional conditions is recommended.

Phytodermatitis

BACKGROUND

Most dermatologists can recognize the classic patterns of presentation of plant contact dermatitis; however, few can recognize the offending plants or know the name and chemical structure of the allergens or irritants that they contain.

OBJECTIVE

Five basic clinical patterns of phytodermatitis are reviewed: 1) allergic phytodermatitis, 2) photophytodermatitis, 3) irritant contact dermatitis, 4) pharmacologic injury, and 5) mechanical injury. The plants responsible for each pattern are presented by families, according to current scientific taxonomy. The chemical structure of the offending substances is described, and principles of investigation, prevention, and treatment are outlined.

CONCLUSIONS

Plant contact dermatitis remains an extremely vast and complex topic. Exotic plants and woods are now present in our gardens and homes. The newfound interest in aromatherapy, phytotherapy, and so-called "natural" therapies is the cause of a tremendous increase in exposure to plant products and extracts. This is responsible for the appearance of atypical patterns of plant contact dermatitis with which the practising dermatologist must become familiar.

Evidence for [2 + 2] photoreaction of alpha-methylene-gamma-butyrolactones with thymine: an explanation for chronic actinic dermatitis to sesquiterpene lactones?

The photoreactivity of isoalantolactone, a natural sesquiterpene lactone, toward thymine was studied. After 313 nm irradiation of a deoxygenated acetone solution of isoalantolactone (2 x 10(-3) M) and thymine (4 x 10(-3) M), two intermolecular [2 + 2] photoadducts, 3 and 4, were isolated with respective yields of 30% and 18%. The structures of these two photoadducts were determined by a combination of NMR experiments. Compound 3 was identified as a cis-syn-exo intermolecular [2 + 2] photoadduct involving the 5,6 double bond of thymine and the exomethylenic double bond of the lactone, while compound 4 was identified as an intermolecular [2 + 2] photoadduct involving the same bonds but with the cis-syn-endo conformation. This high photoreactivity of sesquiterpene lactones toward thymine could be an explanation of the progressive evolution of allergic contact dermatitis toward chronic actinic dermatitis.

Compositae mix is a more sensitive test for Compositae dermatitis than the sesquiterpene lactone mix

Over the past 2 decades, Compositae dermatitis has increasingly been recognized as a cause of exposure-pattern dermatitis. The introduction of the sesquiterpene lactone (SL) mix as a screening test has contributed to this improved recognition. However, there is growing evidence that the SL mix fails to detect a substantial number of genuine Compositae allergies. We therefore investigated whether another screening reagent (the Compositae mix) might be more sensitive in detecting cases of Compositae allergy than the SL mix. Over a 1-year period, we tested 656 consecutive unselected patch test patients to both SL mix and Compositae mix. 31 patients were found to have genuine Compositae allergies. Of these, 28 had reacted to the Compositae mix but only 13 had reacted to the SL mix. The Compositae mix failed to detect only 2 genuine Compositae allergies, whereas the SL mix missed 17 such allergies. On the other hand, the Compositae mix led to 9 irritant reactions, while there was only 1 irritant reaction with the SL mix. We conclude that Compositae dermatitis is still being underdiagnosed with the current screening method, and that the Compositae mix is significantly more sensitive in detecting Compositae allergy than the SL mix.

Occupational allergic contact dermatitis caused by decorative plants

12 cases of occupational allergic contact dermatitis caused by decorative plants were diagnosed in a 14-year period. The patients were middle-aged, and their average exposure time was 13 years. The plant families and plants causing occupational contact dermatitis were Compositae (5 patients; chrysanthemum, elecampane, gerbera, feverfew), Alstroemeriaceae (5 patients, Alstroemeria), Liliaceae (4 patients; tulip, hyacinth), Amaryllidaceae (2 patients; narcissus) and Caryophyllaceae (2 patients; carnation, cauzeflower). The known chemical allergens causing dermatitis were tuliposide-A and sesquiterpene lactones, such as alantolactones and parthenolide, in the Liliaceae and Compositae families. 7 of the 12 patients were able to continue their work; 5 were not because of severe relapses of skin symptoms. The plant allergen and extract series currently available are of great help in the diagnosis.

Delayed-type allergenicity of triforine (Saprol)

The delayed-type allergenicity of triforine (Saprol), 1,4-bis (2,2,2-trichloro-1-formamidoethyl) piperazine, was studied. In a mass examination of chrysanthemum growers among whom triforine was commonly used, the highest rate of positive patch test reaction was seen to triforine (17%) among the 7 pesticides and chrysanthemum extracts tested. A higher prevalence rate of work-related skin symptoms was seen in subjects with a positive patch test reaction to triforine (44%) than in those with negative reactions to all allergens tested (15%) (p < 0.05). 12 subjects (67%) with positive patch test reactions to triforine were also positive to dichlorvos (DDVP), with a high kappa coefficient (0.65). The grading of guinea pig maximization test to triforine was grade IV (66%), defined as "strong". Cross-sensitization between triforine and dichlorvos was also shown. The present results confirm that triforine is capable of including delayed-type allergy among chrysanthemum growers and of showing cross-reactivity with dichlorvos.

Occupational asthma caused by decorative flowers: review and case reports

Occupational respiratory symptoms caused by decorative flowers are seldom reported in the literature. In the years 1985-1993 four such cases of occupational asthma were diagnosed at the Institute of Occupational Health of Finland. Occupational asthma was caused by freesias (n = 1), chrysanthemums (n = 1), and tulips (n = 2). The diagnoses were based on work-related respiratory symptoms during flower handling in the patients' histories, specific challenge tests, and allergologic examinations. Flower allergy is rare but can even develop into occupational asthma. It usually leads to a change of profession.

Pattern of cross-sensitivity between 4 Compositae plants, Parthenium hysterophorus, Xanthium strumarium, Helianthus annuus and Chrysanthemum coronarium, in Indian patients

To assess the pattern of cross-sensitivity between 4 members of the Compositae family, namely Parthenium hysterophorus L., Xanthium strumarium L., Helanthus annuus L. and Chrysanthemum coronarium L., 63 patients clinically diagnosed to have airborne contact dermatitis, and 51 controls having well-defined patterns of contact dermatitis caused by agents other than plants, were patch tested with measured amounts of standardized aqueous extracts of these plants. Positive reactions were obtained in 62 patients and 13 controls with Parthenium hysterophorus, in 47 patients and 9 controls with Xanthium strumarium, in 7 patients and 2 controls with Helianthus annuus, and in 13 of the 57 patients and one out of 28 controls tested with Chrysanthemum coronarium. 2 patients were allergic to all 4 of the plants; 14 patients to 3 plants, namely Parthenium, Xanthium and Chrysanthemum in 9 cases and Parthenium, Xanthium and Helianthus in 5 cases; 32 patients to 2 plants, namely Parthenium and Xanthium in 30 cases, and Parthenium and Chrysanthemum, and Xanthium and Chrysanthemum in 1 case each; 15 patients were allergic to 1 plant only, that being Parthenium. All the 47 patients allergic to Xanthium, 13 patients allergic to Chrysanthemum and 7 patients allergic to Helianthus were positive with some other plant as well. There was 1 patient who was allergic to Xanthium and Chrysanthemum but not to Parthenium. The titre of contact hypersensitivity (TCH) determined in the patients allergic to Parthenium, Xanthium and Helianthus showed values that varied widely with each plant in different patients, and there was no parallelism between the TCH with various plants.(ABSTRACT TRUNCATED AT 250 WORDS)

Sesquiterpene lactone contact sensitivity: clinical patterns of Compositae dermatitis and relationship to chronic actinic dermatitis

A mix of 3 sesquiterpene lactones (SL) (SL mix 0.1%) was evaluated over a 4-year period. Of 7420 patients with eczema investigated by patch testing, 135 (68 male, 67 female) (1.8%) demonstrated positive reactions, 114 (84%) considered clinically relevant. Females outnumbered males until the age of 60, after which men were more commonly affected. The clinical patterns varied from patients presenting with generalized eczema (20%) or eczema of the hands and face (24%), to patients with hand (36%) or facial eczema (11%) alone. 48 patients were investigated for suspected photosensitivity and 29 (21 male, mean age 69 years, and 8 female, mean age 66 years) had abnormal cutaneous monochromatic irradiation tests. These results highlight the varied clinical presentation of SL contact dermatitis and its association with chronic actinic dermatitis. The SL mix proved reliable and safe, supporting its inclusion in the European standard series of contact allergens.

Perturbation of glutathione status and generation of oxidative stress in mouse skin following application of contact allergenic sesquiterpene lactones and isothiocyanates

1. The sensitizing or non-sensitizing status of selected sesquiterpene lactones and isothiocyanates was confirmed in mouse by open epicutaneous application. 2. Glutathione status of mouse skin was determined 12 h after lactone/isothiocyanate application; glutathione S-transferase activity also was determined 12 h after lactone application. 3. NAD(P)H utilization by rat liver microsomal preparations exposed to the sesquiterpene lactones and isothiocyanates was measured. 4. A correlation was observed between sensitizing status and the ability to perturb glutathione status, to induce glutathione S-transferase activity, and to stimulate NAD(P)H utilization. 5. It was concluded that sensitizing sesquiterpene lactones and isothiocyanates could induce oxidative stress in mouse skin, possibly as a result of their reductive metabolism.

A murine in vitro model of allergic contact dermatitis to sesquiterpene alpha-methylene-gamma-butyrolactones

The use of a lymphocyte transformation test (LTT) to provide evidence of allergic contact dermatitis was investigated. The haptens studied were alantolactone and isoalantolactone, two moderate allergens from Inula helenium L., a decorative and medicinal plant. Only alantolactone showed a significant response in vivo and in vitro in mice sensitized epicutaneously, without using Freund's complete adjuvant. Isoalantolactone did not show any sensitizing capacity in the murine model studied. The comparison of in vitro lymphocyte proliferation and in vivo allergenic capacity showed a good correlation and clearly demonstrates that, of the two sesquiterpene lactones, alantolactone is the better sensitizer.

Compositae dermatitis: a survey

Compositae dermatitis in an allergic contact dermatitis, frequently chronic, triggered by plants of the Compositae family. The condition, which is seen, in particular, in middle-aged and elderly persons, typically starts in the summer months with an acute eczema either corresponding to areas exposed to light and air, or corresponding to areas of plant contact; it disappears spontaneously during the fall of the year. Repeated exposure over a number of years may cause severe intractable dermatitis affecting the patient throughout the year. The responsible allergens are sesquiterpene lactones, and investigations to date indicate that the frequency of the allergy is similar to that seen with some of the contact allergens of the standard patch test series. The diagnosis, however, is difficult, partly due to the fact that the clinical picture may be mistaken for a photodermatosis, and partly owing to the difficulty in obtaining commercially available allergens for patch testing. The diagnosis is therefore based on testing with plant extracts, which can cause pronounced local reactions and possibly active sensitization. A survey is given of the possible modes of sensitization, sex and age distribution, the relationship to photosensitivity and atopy, as well as the possible treatment. It is concluded, on the basis of the chronic nature of the disease, and the diagnostic and treatment problems, that continued intensive research into the condition is urgently needed.

A successful murine model for contact sensitization to a sesquiterpene-alpha-methylene-gamma-butyrolactone: sensitization to alantolactone in four strains of mice

Induction of allergic contact hypersensitivity to a sesquiterpene lactone, alantolactone, was studied in four strains of mice: C3H/He, DBA/2, Balb/b, and Balb/c. The last three were successfully sensitized. A significant dose/response was demonstrated in these species, as well as an experimental "overload effect" in Balb/c and Balb/b strains. Histologic studies confirmed the allergic nature of the reaction. From the overall results, alantolactone can be considered a moderate sensitizer in mouse as well as in guinea pig. This study shows that the murine model can be used for experimental contact sensitization with moderate allergens, without the use of Freund's adjuvant for induction.

Patch testing with the "sesquiterpene lactone mix": a marker for contact allergy to Compositae and other sesquiterpene-lactone-containing plants. A multicentre study of the EECDRG

6278 patients were patch tested with a sesquiterpene lactone mix (SL-mix) in 10 European clinics. 4011 patients were tested only with 0.1% SL-mix, 63 (approximately 1.5%) of whom were positive, with 26 (41%) of these cases being considered clinically relevant. There were no cases of active sensitization, though 5 cases of irritation were reported. 22 irritant reactions and 22 cases of active sensitization occurred when testing also with 1% and 0.33% concentrations of SL-mix. SL-mix 0.1% pet. is shown to be an important patch test and many relevant sensitizations will be missed without routine screening with such a mix. Most patients with SL-mix sensitivity presented with hand and/or face dermatitis, apparent photodermatitis or more generalised eczema.