Abstract: Objective: To detect the level of IL-35 in peripheral blood of the patients with chronic spontaneous urticaria (CSU) and to determine the inhibitory effect of IL-35 on mast cell-activated vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs). Methods：Peripheral blood from 30 patients with CSU and 30 healthy controls (HC) was collected. The concentrations of serum IL-35 and soluble VCAM-1 (sVCAM-1) were detected by Luminex 200. Mast cells were cultured in vitro and co-incubated with peripheral serum for 24 hours, then the supernatant was collected. After that, the supernatant and IL-35 were co-cultured with HUVECs, which were divided into the control group (only contains RPMI 1640 medium), healthy people supernatant group (HC), CSU supernatant group (CSU), HC+IL-35 group and CSU+IL-35 group. The level of VCAM-1 protein was detected by flow cytometry, and the adhesion of mononuclear cells and endothelial cells was detected by fluorescence microscopy. Results: Compared with the healthy controls, the concentration of serum IL-35 was significantly reduced and the serum sVCAM-1 concentration was significantly increased in the CSU patients (Ps<0.05). The concentration of serum IL-35 was negatively correlated with sVCAM-1 in CSU patients (r=-0.5232 P=0.003). The expression of VCAM-1 in HUVECs and the adhesion of PBMCs to HUVECs in IL-35+CSU group were significantly lower than those in the CSU group (Ps<0.05). Conclusions: The concentration of serum IL-35 is decreased in CSU patients and up-regulation of IL-35 concentration can inhibit the activation of vascular endothelial cells by mast cells.

Key words: chronic spontaneous urticaria, interleukin-35, endothelial cells, vascular cell adhesion molecule-1