Correlation Between Food-specific IgG Antibodies And Phenotypes Of Chronic Spontaneous Urticaria

Objective: To investigate correlations between food-specific immunoglobulin G(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 March2015.Enzyme-linked immunosorbent assay was conducted to detect serum levels of 90food-sIgG antibodies and total immunoglobulin E(t IgE)antibodies,Western blot analysis to detect levels of 20 allergen-specific immunoglobulin E(sIgE)antibodies,and chemiluminescent microparticle immunoassay to detect levels of anti-thyroid peroxidase immunoglobulin G(TPO-IgG)antibodies and anti-thyroglobulin immunoglobulin G(TG-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 and among several groups were performed by Mann-Whitney U test and Kruskal-Wallis test,respectively;multiple significant test was performed by Bonferroni method;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 sIgG serum level of ≥ 100 U/ml(at least 2+)was defined as positive sIgG antibodies,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(11/15,73.33%)than in the healthy controls(7/13,53.85%).The sIgE serum level of ≥ 0.7 k U/L(at least 2+)was defined as positive sIgE antibodies,and the positive rate of allergen-sIgE antibodies was26.21%(65/248)in the patients with CSU,22.73%(5/22)in the patients with SD,none in the patients with AU(0/15),and 23.07%(3/13)in the healthy controls.Among the CSU patients:1.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);2.The proportion of patients with allergic comorbidities was significantly higher in the sIgG-positive but sIgE-negative group(40/124,32.26%)than in the both sIgG and sIgE-negative group(9/59,15.25%,χ2 = 5.90,P = 0.020);3.The serum level of t IgE was significantly higher in the sIgE-positive group [130.74(69.70,220.69)IU/ml]than in the sIgE-negative group [107.80(45.00,183.00)IU/ml,Z =-2.06,P = 0.039],and higher in the sIgG-negative but sIgE-positive group [157.34(118.76,271.38)IU/m L] than in the sIgG-positive but sIgE-negative group [107.41(41.66,179.77)IU/m L,Z =-2.65,P =0.008];4.The mean age in the both TPO-IgG and sIgG-positive group(46.39 ± 11.42)was significantly older than that in the both TPO-IgG and sIgG-negative group(38.73 ± 12.38,F= 3.14,P’ = 0.020);5.The proportion of patients with allergic comorbidities was significantly higher in the both TPO-IgG and sIgG-positive group(12/33,36.36%)than that in the both TPO-IgG and sIgG-negative group(7/59,11.86%;χ2 = 7.75,P’ = 0.008);6.The proportion of angioedema was significantly higher in the both TPO-IgG and sIgG-positive group(15/33,45.45%),TPO-IgG-negative but sIgG-positive group(38/143,26.57%)and TPO-IgG-positive but sIgG-negative group(9/13,69.23%)than that in the both TPO-IgG and sIgG-negative group(7/59,11.86%,χ2 = 13.12、5.22、20.28,P’ < 0.001、= 0.025、< 0.001),respectively;7.The mean age in the sIgE-negative but TPO-IgG-positive group(45.22 ±13.50)was significantly older than that in the sIgE-positive but TPO-IgG-negative group(38.48 ± 11.88,F = 2.91,P = 0.049);8.The proportion of angioedema was significantly higher in the sIgE-negative but TPO-IgG-positive group(19/37,51.35%)than that in the both sIgE and TPO-IgG-positive group(30/146,20.55%,χ2 = 14.28,P < 0.001);9.No significant difference was observed in the urticaria activity score for 1 day(UASday)and the required dosage of second-generation H1-antihistamines between the sIgG-positive group and sIgG-negative group,and between sIgE-positive group and sIgE-negative group.Conclusion: The prevalence of family history of allergic diseases was relatively high in food-sIgG-positive patients with CSU.Food-sIgG could not be used as an indicator to reflect the disease activity of CSU or as a guide for treatment.