2.2 Application and evaluation of skin prick test
Skin prick tests were applied on the anterior surface of the forearm when they were appropriate for test such as they were not taking antihistamines. Histamine (10 mg/ml) and physiological saline were used as positive and negative references, respectively. Skin reactions were evaluated 20 min after the application of the skin test, and indurations of 3 mm was considered indicative of a positive reaction. Skin prick tests Skin prick tests including: Dermatophagoides pteronyssinus, Dermatophagoides farinea, artemisia powder,phoenix tree pollen, birch pollen, cockroach, mold, shrimp, cat and dog dander (Peking Union Medical College Hospital, Peking, China). A positive reaction was characterized as 3 mm or greater than that of the negative control. Skin prick test for the same allergens was performed for all patients.