[The plasma level and gene expression in peripheral blood of interleukin-35 in patients with sarcoidosis and its clinical significance]

Objective: To investigate the expression of interleukin(IL)-35 protein and gene in peripheral blood of patients with sarcoidosis and its clinical significance. Methods: Peripheral blood samples from 98 patients with sarcoidosis and 98 healthy volunteers were collected at Peking Union Medical College Hospital between January 2016 and March 2017. The plasma levels of IL-35 were detected by enzyme-linked immunosorbent assays (ELISA), and the relationship between IL-35 and the clinical characteristics was analyzed. Real-time quantitative PCR was used to detect the expression levels of IL-35 subunit EBI3, p35 and T regulatory cell transcription factor Foxp3 mRNA in peripheral blood mononuclear cells, and their correlations were analyzed. Results: The plasma levels of IL-35 in patients with sarcoidosis (44±12) ng/L was significantly lower than that in the normal control group (55±12) ng/L (P<0.001). There was a positive correlation between the plasma levels of IL-35 and D(L)CO% predicted values (r=0.76, P<0.001), but it showed no significantly correlation with other clinical parameters. The expression of EBI3 and Foxp3 mRNA in peripheral blood mononuclear cells of patients with sarcoidosis (1.54±0.74, 0.92±0.36) were significantly lower than those in the normal control group respectively (2.12±0.61, 1.10±0.27, all P<0.05). There was a significant positive correlation between the expression of EBI3 and Foxp3 mRNA in the sarcoidosis group (r=0.786, P<0.001). Conclusion: IL-35 may be involved in the inflammatory process of sarcoidosis and play an important role in the pathogenesis of the disease.