Abstract: Objective To observe the changes of expression levels of serum soluble ST2 (sST2), interleukin-33 (IL-33), and their regulation effects on Th17 / Treg cell immune balance in primary immune thrombocytopenia (ITP), and to investigate the possible immune mechanism of sST2 and IL-33 in ITP. Methods A total of 30 patients with ITP were regarded as ITP group, and 20 healthy subjects were used as healthy control group. ELISA method was used to detect the serum levels of sST2, IL-33, IL-17 and TGF-β in two groups. Results Compared with the normal control group, the serum levels of sST2 and IL-17 were increased (P＜0.01), the serum level of TGF-β was decreased in ITP group (P＜0.01). There was no significant change in serum level of IL-33 between the two groups (P＞0.05). The correlation analysis showed that sST2 was negatively correlated with TGF-β in ITP group (r=-0.471, P＜0.01), and there was no correlation in sST2 and IL-17 (r=0.189, P＞0.05). Conclusion The increased expression of sST2 and the imbalance of Th17/Treg may be one of the key immunomechanisms of ITP.

Key words: interleukin-33, interleukin-17, transforming growth factor-beta, primary immune thrombocytopenia, soluble ST2