Letter to the Editor: Two Major Phenotypes of Sulfite Hypersensitivity: Asthma and Urticaria

• The authors have no financial conflicts of interest. which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The sulfites are widely used as anti-browning agents and preservatives in food, cosmetics and medicine. The use and amount of sulfites in products have recently been regulated by the Food and Drug Administration (FDA) and the Korean FDA; however, sulfite hypersensitivity reactions, ranging from bronchoconstriction, 1 ur-ticaria, 2 contact dermatitis 3 to life threatening anaphylaxis, 4 are still being reported. 5 To date, this is the first study to compare two major phenotypes of sulfite hy-persensitivity, asthma and urticaria, in this country. Moreover, we carefully analyzed the clinical features of sulfite sensitive asthma, and compared them with those of sulfite tolerant asthma. We retrospectively analyzed the medical records of 26 sulfite hypersensitivity subjects confirmed by a sulfite oral provocation test (OPT). As a control group, 61 asthmatic patients negative to sulfite OPT were enrolled from Ajou University Hospital, Suwon, Korea. We performed sulfite oral provocation test on the subjects who were resistant to conventional treatment of asthma/urticaria or who had histories of allergy to sulfite containing food such as wine, dried fruits, or salads from buffet. To confirm sulfite sensitivity, we conducted single blind placebo controlled provocation test. After the asthmatic patients showed no response to gelatin capsule (EMBO CAPS lot. 051A51-22306, Suheung Capsule, Seoul, Korea) with 2 hours observation, they were administered sodium metabisulfite (Na2S2O5; Sigma Co., St. Louis, MO, USA) starting from 40 mg and increasing to 100-200 mg via gelatin capsule vehicle. The reactions were observed for 2 hours each until the hy-persensitivity reactions developed, 1 maximally 6 hours. Especially for broncho-constriction reaction, 1) a decline in FEV1 of 20% or greater, or 2) a decline in FEV1 of 15% to 20% compared to the baseline with definite symptoms/signs of sulfite hypersensitivities (such as wheezing, cough or dyspnea) were considered positive. Pulmonary function tests were repeated at 30 minute intervals. 6 In the case of urticarial reaction, sulfite OPT was defined as positive when hives arise; however, it was classified as negative if subjective pruritus developed. Subjects were classified into group I: sulfite sensitive asthma, group II: sulfite sensitive urti-caria and group III: sulfite tolerant asthma according to their sulfite OPT reaction. In addition, group I included two patients with concurrent sulfite anaphylaxis.