Abstract: 【Abstract】 Objective To explore the relationship of serum interleukin （IL）-9 and platelet-activating factor （PAF） levels with serum total immunoglobulin E （IgE） levels, disease severity and disease course in patients with chronic spontaneous urticaria（CSU）. Methods A total of 60 patients with active CSU were collected from Department of Dermatology, the First Affiliated Hospital of Hebei North University from March 2018 to March 2019 （active CSU group） , and divided into mild group, moderate group and severe group according to 7-day urticaria activity score （UAS7）. After 28-day standard antihistamine therapy, the patients whose condition became stable were included in the stable CSU group. During the same period, 30 health examinees were included in the healthy control group. Peripheral venous blood samples were collected from the subjects in each group, enzyme-linked immunosorbent assay （ELISA） was performed to detect serum levels of IL-9 and PAF, and immunoturbidimetric assay to detect the serum total IgE level. Correlations of serum IL-9 and PAF levels with serum total IgE levels, UAS7 scores and course of disease were analyzed in patients with CSU. One-way analysis of variance was used for comparisons among multiple groups, least significant difference-t test for multiple comparisons, and Pearson correlation analysis for correlation analysis. Results Totally, 28 males and 32 females were included in the active CSU group, their age ranged from 11 to 68 years （34.68 ± 8.62 years）, and the disease duration ranged from 2 months to 7 years （1.42 ± 0.41 years）. In the healthy control group, 14 were males and 16 were females, and their age ranged from 10 to 70 years （35.06 ± 7.89 years）. According to UAS7, 12, 26, and 22 patients were diagnosed with mild, moderate and severe CSU respectively, and 22 were included in the stable CSU group after standard treatment. The levels of serum IL-9, PAF and total IgE significantly differed among the active CSU group, stable CSU group and healthy control group （IL-9: 144.34 ± 23.19 vs. 109.25 ± 20.77 vs. 107.23 ± 19.23 pg/ml; PAF: 362.45 ± 51.45 vs. 223.18 ± 32.46 vs. 221.23 ± 28.38 pg/ml; total IgE: 168.12 ± 32.48 vs. 24.04 ± 7.04 vs. 21.76 ± 5.95 IU/ml; F = 38.80, 148.38, 499.12, respectively, all P < 0.001）, and were significantly higher in the active CSU group than in the stable CSU group and healthy control group （all P < 0.05）, while there was no significant difference between the stable CSU group and healthy control group （all P > 0.05）. Pearson correlation analysis showed that the serum IL-9 and PAF levels were positively correlated with serum total IgE levels and UAS7 scores （P < 0.05）, but not correlated with the disease course （P > 0.05）. Conclusion Serum IL-9 and PAF levels in patients with active CSU were markedly elevated along with the increase in disease severity, and closely correlated with serum total IgE levels.

Key words: Urticaria, Interleukin-9, Platelet-activating factor, Immunoglobulin E, UAS7 score