Elisabeth Gäfvert

Isolated colophony allergens as screening substances for contact allergy

Rosin has a complex chemical composition. The aim of this study was to investigate if it is possible to define 1 or 2 compounds as the rosin allergens. 2 compounds, 13, 14(β)‐epoxyabietic acid and 7‐oxodehydroabietic acid, identified in gum rosin and tall oil rosin, were used as screening substances for patch testing in addition to the standard series. The rosin patch detected more cases of contact allergy than the isolated allergens did. Our suggestion is to patch test with a preparation of gum rosin, as well‐defined as possible, for screening. The content of oxidation products should be kept at a constant and rather high level, since these are the main allergens. A rosin series for additional testing of patients with allergic contact dermatitis suspected to be caused by rosin could he a valuable tool. Gum rosin and tall oil rosin from different countries should be included, since the amounts of allergens in rosin varies due to source and mode of production. Testing with identified allergens from modified rosin products and with modified rosins could also be performed.

Patch testing with allergens from modified rosin (colophony) discloses additional cases of contact allergy

Most rosin (colophony) used today is chemically modified. Will contact allergy 10 modified rosin be overlooked when testing is performed with only unmodified rosin in the standard series? 2 components from modified rosins. maleopimaric acid (MPA) and glyceryl 1‐monoahietale (GMA), earlier identified us contact allergens, were added to the patch lest standard series. Some commonly‐used modified rosin products were also tested. Positive reactions were observed to the modified components MPA and GMA. Of the patients with positive reactions to MPA and GMA. several did not react to unmodified rosin in the standard series. No reaction was observed to the modified rosin products without a concomitant reaction to unmodified rosin. The positive reactions observed to the modified rosins may be due to residual unmodified material in the product, but a possible contribution from allergenic modified rosin components cannot be disregarded. When u patients history indicates a rosin allergy, but a negative response to unmodified rosin in the standard series is observed, additional testing with GMA and MPA or, second best, with glycerol‐esterified rosin and maleic‐anhydride‐modified rosin is recommended. Some modified rosin products, which could be used for additional testing, are suggested.

Airborne contact dermatitis from unexpected exposure to rosin (colophony). Rosin sources revealed with chemical analyses.

We report 3 cases of contact dermatitis in rosin‐sensitive individuals caused by exposure to airborne rosin components from different sources. Case no. 1 was a female office worker with a facial dermatitis caused by rosin components which emanated from the linoleum floor covering in her office. Floor material containing wood flour and rosin was released into the air, causing a facial dermatitis in the rosin‐sensitive subject. Case no. 2 involved a woman who worked in a factory producing dairy product cartons and had a dermatitis on her lower legs, lower arms and upper chest. Her dermatitis was caused by dust from the paper cartons and contact allergy to rosin components probably aggravated her dermatitis. Case no. 3 was a female office worker with a relapsing dermatitis on her eyelids. Her dermatitis was caused by a rosin‐containing floor polish, which was seen as a powder on the office floor. Extracts of suspected material and products were patch tested and analysed for the presence of rosin components with HPLC and GC techniques. A discussion and recommendations on chemical analyses of rosin components follow. We conclude that a thorough investigation, including chemical analyses, can rule out non‐specific diagnoses and offer a solution to the patients skin problems.

Mechanism of the antigen formation of carvone and related alpha, beta-unsaturated ketones

In the present study, the mechanism for the antigen formation of α, β‐unsaturated ketones was investigated. A series of analogues of carvone ((5R)‐5‐isopropenyl‐2‐methyl‐2‐cyclohexenone) with altered chemical reactivity and with retained overall structure or with retained reactivity and altered three‐dimensional structure were synthesized. These analogues were tested for cross‐reactivity in carvone‐sensitized animals. Cross‐reactivity was observed for analogue 3 ((5R)‐5‐isopropyl‐2‐methyl‐2‐cyclohexen‐1‐one). No cross‐reactions were observed for analogues 1 ((2R,5R)‐5‐isopropenyl‐2‐methyl cyclohexanone) and 4 ((5R)‐2,3‐dimethyl‐5‐isopropenyl‐2‐cyclohexene‐1‐one). Both those compounds also failed to induce sensitization. These findings demonstrate that α, β‐unsaturated ketones form antigens after a nucleophilic attack at the β‐carbon with soft nucleophiles such as thiol in cysteine and not with the formation of a Schiff’s base after a nucleophilic attack at the carbonyl carbon with nitrogen nucleophiles. Furthermore, no cross‐reactivity was observed between R‐ and S‐carvone indicating the importance of the 3‐dimensional structure of haptens (and antigens) in T‐cell recognition. The analogues were also tested for cross‐reactivity on patients allergic to carvone. The results from the animal study were confirmed.

Different physical forms of maleopimaric acid give different allergic responses

Endo‐maleopimaric acid (MPA) is a contact allergen formed when colophonium is “modified” with maleic anhydride or fumaric acid. Previous patch testing showed a higher allergic response to petrolatum (pet.) preparations of MPA in amorphous form compared to MPA in crystalline form. In the present study, the impact of the physical form of MPA on the allergic response was investigated. Since the amorphous form is difficult to standardize, crystalline MPA mechanically incorporated or dissolved in pet. was used. A lower eliciting capacity was obtained from crystalline MPA, compared to that obtained from dissolved MPA, in guinea pigs intradermally induced with MPA. Using 3H‐MPA a 3× difference in the dissolution into synthetic sweat from MPA dissolved in pet., compared to MPA mechanically incorporated, was demonstrated. A difference in bio‐availability between dissolved and crystalline MPA could therefore be assumed. Crystalline MPA had a low sensitizing capacity compared to that seen for amorphous MPA in previous studies. The amorphous form of MPA is likely to have a larger surface area than crystalline MPA, with less ordered molecules, resulting in a higher dissolution rate and a greater bio‐availability. Modified colophonium exists as amorphous solids and as viscous liquids. Thus, exposure will probably be to non‐crystalline MPA and cases of contact allergy could be overlooked when screening with crystalline MPA.

Isolation and Identification of Contact Allergens

A major preventive step in the field of allergic contact dermatitis is the detection and identification of the offending allergen in the products present in the patient’s environment, both at home and at work. In many cases it is difficult to patch test properly with technical products suspected to be the cause of an allergic contact dermatitis. Irritation from a product will hide a potential allergenic activity at patch testing. In other cases, the concentration of the offending agent in a product may be too low to elicit a reaction in the limited area of a single patch test. If possible, the ingredients of a product suspected to cause contact dermatitis should be tested separately.

Patch testing with maleopimaric acid in an occupational dermatology clinic

Patients and Methods 205 consecutive patients referred for further investigation of suspected occupational dermatitis were patch tested with a modified European standard series containing colophony (20% pet., Chemotechnique Diagnostics AB, Malmö, Sweden). The patients were also patch tested with other relevant series and allergens, as well as MPA. MPA was synthesized as previously described (1, 2). The previously established patch test concentration of 1.2% (pet.) was used (3). Patch testing (2day occlusion), reading (on days (D) 2, 3, and 4 or 6) and scoring were according to the recommendations of the ICDRG.