High frequency of false-positive reactions in attempted patch testing with acrylate/methacrylate mixes.

Background: Although acrylate/methacrylate allergy has been frequently reported, until now patch testing with this group of allergens has been unwieldy, requiring the application of large supplementary series in most centres. Objectives: To formulate and evaluate two mixes of acrylate/methacrylate allergens in three centres (Malmo, Singapore, and Leuven). Patients/materials/methods: All patients tested with the baseline series during the study period were also patch tested with the mixes. Mix 1 consisted of: triethyleneglycol diacrylate (TREGDA) 0.1% wt/wt, 2-hydroxyethyl methacrylate (2-HEMA) 1.0% wt/wt and ethyleneglycol dimethacrylate 1.0% wt/wt in petrolatum. Mix 2 consisted of: TREGDA 0.1% wt/wt and 2-HEMA 2.0% wt/wt in pet. The separate components of the two mixes were also tested simultaneously. Results. There were 25 (5 males; 20 females) positive reactions to mix 1 with 16 in Malmo, 8 in Singapore, and 1 in Leuven. Positive reactions to mix 2 were seen only in Malmo, in 8 female patients. Thus, the positive reaction rate for mix 1 was 8.3% overall (Malmo 7.7%, Singapore 18.6%, and Leuven 2.1%), and that for mix 2 was 2.7% overall (Malmo 3.8%, Singapore 0%, and Leuven 0%). Of the 16 positive reactions to mix 1 in Malmo, only 4 were considered to be true allergic reactions, as the component allergen testing gave totally negative results in 12/16. For mix 2, only 3/8 positive reactions were considered to be true allergic reactions, as the component testing was negative in 5/8. Many doubtful (10-20%) and positive but non-allergic reactions were recorded, leading to early termination of the study. Conclusions: Although this was an unsuccessful attempt to formulate an acrylate/methacrylate mix, our experience will be useful for those embarking on future attempts to do this. (Less)