Spectrum of cross-photosensitization in 18 consecutive patients with contact photoallergy to ketoprofen: associated photoallergies to non-benzophenone-containing molecules.

Contact photoallergy to ketoprofen gels has been widely reported, and cross-sensitivity reactions with other compounds, such as tiaprofenic acid, fenofibrate and benzophenones, are well known. However, positive photopatch tests to other different non-benzophenone-related compounds have recently been observed. We report the results of photopatch testing in patients with contact photoallergy to ketoprofen and discuss the spectrum of cross-sensitization to ketoprofen. 18 consecutive patients with a history of photocontact dermatitis from ketoprofen were investigated. Patch and photopatch tests were performed. As expected, we observed positive photopatch tests to Ketum* gel and ketoprofen 2.5% in petrolatum in all patients (100%). However, it was remarkable to note positive photopatch tests to other unexpected and non-relevant allergens, including fentichlor (67%), tetrachlorosalicylanilide (28%), triclosan (17%), tribromsalan (11%) and bithionol (11%), with no clinical relevance. Interestingly, these agents belong to the family of halogenated salicylanilides and related compounds, which have been forbidden in Europe since the 1970s. Our results raise the question of hyper-photosusceptibility to non-relevant allergens induced by photosensitivity to ketoprofen. The mechanism may involve the high photoreactivity induced by the association of a benzene ring with an oxygen group.

[Photocontact dermatitis due to ketoprofen and photosensitization to tetrachlorosalicylanide and to Fenticlor(R)]. / Photoallergie au kétoprofène et photosensibilisations au tétrachlorosalicylanide et au Fenticlor(R).

BACKGROUND: Photoallergy to ketoprofen and cross reactivity of ketoprofen with diphenylketones are well known; here are some cases of photoreaction to ketoprofen and unusual substances. PATIENTS AND METHODS: Eleven photoallergic to ketoprofen patients were photo patch tested with Ketum(R), ketoprofen, oxybenzone, tiaprofenic acid, fenofibrate, and also chlorphenesin, sunscreen series, and photobiologists series (without lichen mix and benzocaine). We performed tests at day 0, we irradiated them with UVA at day 2, and control series remained closed. We performed readings at day 3 and 4 according to ICDRG's recommendations. RESULTS: Nine tested patients had positive reactions to the irradiated tests with no expected allergens: fenticlor (9 cases), halogenated salicylanilides (4 cases), dibenzoylmethane (3 cases) and cinnamate (1 case). DISCUSSION: The mechanism of these unusual photosensitizations is discussed. These cases show that it is important to test sunscreen series and photobiologists series in patients photoallergic to ketoprofen.

Cross-reactivity between terrestrial snails (Helix species) and house-dust mite (Dermatophagoides pteronyssinus). I. In vivo study.

Clinical reports have suggested an unusual frequency in the number of patients with food allergy to snails who are also allergic to the house-dust mite (HDM). As allergy to HDM is one of the most frequent sensitizations in atopic patients of Western countries, evaluation of the relevance of the concomitant sensitization to Dermatophagoides pteronyssinus and to snails is an important consideration. To evaluate the responsibility of different snail components and of snail mites for inducing in vivo hypersensitivity in patients allergic to HDM, the in vivo reactivity of patients with clinical symptoms after ingestion of snails was assessed by skin prick tests with extracts and hemolymph from four different Helix species snails, and extracts from the snail parasitic mite, Riccardoella limacum. In addition, to obtain epidemiologic data on cosensitization to HDM and snails in allergic patients, the frequency of snail sensitization and its relationship to HDM sensitization were determined in a population of 169 allergic children. All patients allergic to snails had positive skin prick tests to the snail extracts and none to R. limacum extract. The number of positive skin reactions did not significantly differ whatever the species, snail part, or heating procedure used. The strongest reactions were obtained with Helix pomatia (Burgundy snail). Among the 169 prospectively tested children, 38 had a positive prick test to snail extracts; 79% of the snail-sensitized children had sensitization to HDM; and 31% of the children allergic to HDM were found to be sensitized to snails. These results show that snail components, and not the mite R. limacum, were responsible for the in vivo hypersensitivity. These snail components reacting in vivo are present in different parts of snails, including the hemolymph. One-third of the children allergic to HDM were sensitized to snails without any previous ingestion of snails: this observation suggests that HDM was the sensitizing agent and that the cross-reaction could be clinically relevant in countries where eating snails is common.

Cross-reactivity between terrestrial snails (Helix species) and house-dust mite (Dermatophagoides pteronyssinus). II. In vitro study.

Epidemiologic and in vitro data have shown that the association of house-dust mite (HDM) allergy and snail allergy in the same patients was due to cross-reactivity between HDM and snail allergenic components. However, the cross-reacting allergen(s) have not yet been identified. In vitro reactivity of seven patients' sera to the various extracts and hemolymph of four different Helix snail species was analyzed by IgE detection and immunodots and Western blots. Cross-reactivity between snails and Dermatophagoides pteronyssinus was assessed by immunodot and ELISA inhibition in two patients. Heterologous inhibition of the snail immunodot and ELISA was observed in one serum. Western blotting showed a specific binding on all four snail species extracts; molecular weights of snail allergens ranged from < 21 to 200 kDa. Marked individual differences were observed in the seven sera under study; most sera demonstrated IgE recognition of multiple bands, illustrating that no single allergen is responsible for cross-reactivity between snail and mite. These results confirm that cross-reactivity exists between snails of the Helix genus and HDM. This cross-reactivity, involving more than a single allergen, may be of clinical significance in atopic patients allergic to D. pteronyssinus. The identity of the cross-reacting allergens remains to be determined. Potential candidates include the thermostable minor allergens of D. pteronyssinus, tropomyosin and hemocyanin.

[A new allergen dibromodicyanobutane. Report of a study in 310 patients January-December 1994]. / Un nouvel allergène: le dibromodicyanobutane. Compte rendu d'une étude portant sur 310 malades de janvier a décembre 1994.

INTRODUCTION: Methylisothiazolinone chloride (Kathon CG) and its derivatives, used as preservatives in cosmetics, have been shown to be allergenic when used in humans although preliminary studies in Guinea pigs failed to reveal any sensitization. Dibromodicyanobutane, associated with phenoxyethanol in Euxyl K400, has been proposed to replace the isothiazolinone derivatives in cosmetics. Preliminary study has shown that these thiazolinone derivatives are not allergenic in Euxyl K400. The similarity of these situations led us to hypothesize that dibromodicyanobutane could become allergenic. METHODS: We tested 0.1 p. 100 dibromodicyanobutane in vaseline in the additional battery of the ICDRG battery in patients with contact eczema. Among the 310 patients tested, 1.94 p. 100 had a positive test for this allergen (during this same period, 1.29 p. 100 of the patients were positive for isothiazolinones). Three patients were hospitalized because of generalized eczema and 1 patient had changed occupation with no effect because the crems containing the allergen had not been avoided. CONCLUSION: Dibromodicyanobutane is a new allergen. Numerous cases of allergy have developed as use of the product becomes more widespread. The consequences of this sensitization may have an economic impact. Animal experimentation has been unable to predict this allergenic effect. Cosmetic products must be precisely labeled with a single international term for each specific molecule and the name of the preservative added to the active substance.