Abstract: 【Abstract】 Objective To investigate the correlation between food-specific IgG （sIgG） antibodies and phenotypes of chronic spontaneous urticaria （CSU）. Methods Serum samples were collected from outpatients with active CSU, symptomatic dermographism （SD）, or acute urticaria （AU）, and healthy controls from 5 third-grade class-A hospitals such as the First Hospital of China Medical University between April 2014 and March 2015. Enzyme-linked immunosorbent assay was conducted to detect serum levels of 90 food-sIgG antibodies and total IgE, Western blot analysis to detect levels of 20 allergen-specific IgE antibodies, and chemiluminescent microparticle immunoassay to detect levels of anti-thyroid peroxidase IgG antibodies and anti-thyroglobulin IgG antibodies. Comparisons of normally distributed quantitative data between two groups and among several groups were performed by t test and one-way analysis of variance, respectively; comparisons of non-normally distributed quantitative data between two groups were performed by Mann-Whitney U test; for comparisons of proportions, chi-square test and Fisher′s exact test were used. Results A total of 248 patients with CSU, 22 with SD, 15 with AU and 13 healthy controls were recruited. The cut-off level for sIgG positivity was 100 U/ml （at least 2+）, and the positive rate of food-sIgG antibodies was slightly higher in the patients with CSU （176/248, 70.97%）, SD（15/22, 68.18%）and AU（11/15） than in the healthy controls （7/13; χ2 = 1.80, P = 0.615）. Among the 248 CSU patients, the proportion of patients with family history of allergic diseases was significantly higher in the sIgG-positive group （71/176, 40.34%） than in the sIgG-negative group （19/72, 26.39%; χ2 = 4.30, P = 0.042）, while no significant difference was observed in the 1-day urticaria activity score （UASday） between the two groups （Z = 0.18, P = 0.859）. Totally, 177 CSU patients completed 12- to 40-week treatment; their condition could be completely controlled by second-generation H1-antihistamines, and there was no significant difference in the required dosage of second-generation H1-antihistamines between the sIgG-positive group （128 cases） and sIgG-negative group （49 cases; Z = -1.06, P = 0.298）. Conclusions The prevalence of family history of allergic diseases was relatively high in food-sIgG-positive patients with CSU. However, food-sIgG could not be used as an indicator to reflect the disease activity of CSU and treatment response.

Key words: Urticaria, Chronic spontaneous urticaria, Symptomatic dermographism, Acute urticaria, Food-specific IgG antibody, Thyroid peroxidase, Thyroglobulin, Total IgE antibody, Allergen-specific IgE antibody