Expression of complement receptor type 1 on erythrocytes and its correlation with immunoglobulin E,complement C3 and C4 expressions in patients with chronic urticaria

Abstract

Objective To investigate the role of erythrocyte complement receptor type 1 (CR1) in the pathogenesis of chronic urticaria.Methods Venous blood samples were collected from 59 patients with chronic urticaria (including 14 cases of dermatographism and 45 chronic idiopathic urticaria) and 29 healthy human controls.Flow cytometry was carried out to quantify the expression level of CR1,and double-antibody sandwich enzyme-linked immunosorbent assay to determine the serum level of immunoglobulin E (IgE),complement C3,C4 and 50％ complement hemolytic activity (CH50).Differences in these parameters were analyzed by one-way ANOVA and independent samples t-test,and correlation between these paramenters by Pearson correlation analysis.Results The expression level (expressed as mean fluorescence intensity per 10 000 erythrocytes) of CR1 was significantly higher in patients with dermatographism and chronic idiopathic urticaria than in the healthy controls (35.06 ± 2.06 and 29.17 ± 1.53 vs.20.46 ± 2.57,t =4.20 and 3.33,both P ＜ 0.05),while no statistical difference was observed between the patients with dermatographism and chronic idiopathic urticaria (P ＞ 0.05).Increased total serum IgE levels were observed in patients with dermatographism and chronic idiopathic urticaria compared with the healthy controls ((769.89 ± 123.0) μg/L and (340.09 ± 29.74) μg/L vs.(107.63 ± 88.79) μg/L,t =5.58,5.85,both P ＜ 0.05),and in patients with dermatographism compared with those with chronic idiopathic urticaria (t =3.49,P ＜ 0.05).For patients with chronic urticaria,there was a statistical difference in the expression level of CR1 between individuals (n=22) with total serum IgE levels ranging from 0 to 240 μg/L and those (n =17) higher than 500 μg/L (24.45 ± 10.83 vs.33.09 ± 11.86,t =3.33,P＜ 0.05).The total serum IgE levels were positively correlated with the level of CR1 (r =0.27,P ＜ 0.05),but uncorrelated with that of complement C3 (r =0.16,P ＞ 0.05) or C4 (r =-0.08,P＞ 0.05).The level of complement C3 was positively correlated with that of C4 (r =0.54,P ＜ 0.01).One-way ANOVA revealed no significant difference in the serum levels of complement C3,C4,or CH50 between the patients with dermatographism,patients with chronic idiopathic urticaria and healthy controls (all P ＞ 0.05).Conclusion CR1 is abnormally expressed in patients with chronic urticaria. Key words: Urticaria; Receptors, complement; Complement C3; Complement C4; Immunoglobulin E