Abstract: Objective: To determine the expression of Th1 and Treg cells in patients with chronic spontaneous urticaria (CSU) and observe the role of ICOS/ICOSL signaling between peripheral blood T/B cells in CSU. Methods: The expression of Th1, Treg cells, and surface ICOS in peripheral blood, and surface ICOSL on B cells was analyzed by flow cytometry. Results: The proportions of ICOS+ Th1 cells and ICOS+ Treg cells in patients were (15.19±21.96)% and (60.04±31.82)% respectively, significantly higher than those in the control group, which were (2.24±2.62)% and (48.72±19.13)% respectively, and the differences were statistically significant (both P＜0.05). Th1 and ICOS+ Th1 cells were positively correlated with eosinophils (r=0.4998, 0.4701, Ps＜0.05), and ICOS+ Treg cells were negatively correlated with neutrophils (r=-0.3771, P＜0.05). In addition, Th1 cells were positively correlated with CD19+ B cells, and ICOS+ Th1 cells were positively correlated with CD19+ICOSL+ B cells (r=0.5218, 0.5616, Ps＜0.05), while ICOS+ Treg cells were negatively correlated with CD19+ B cells and CD19+ICOSL+ B cells (r=-0.4183, -0.4519, Ps＜0.05). Conclusion: The proportions of ICOS+ Th1 and ICOS+ Treg cells in the peripheral blood of CSU patients are significantly increased, and their correlation with eosinophils and neutrophils as well as CD19+ICOSL+ B cells suggests a potential role of the ICOS/ICOSL pathway in the immune regulation of CSU.

Key words: chronic spontaneous urticaria, Th1 cell, Treg cell, ICOS/ICOSL, B cell