Evaluation of Regulatory B Cells and Serum IL-10 Concentration in Peripheral Blood of Women with Recurrent Pregnancy Loss

Background: Although the role of B cells in normal pregnancy has been recently highlighted, their importance and function are not completely clarified. Until now, some investigations have shown that during pregnancy, regulatory B cells (Breg), a subset of B cells, are one of the key players in immune regulation by both producing IL-10 and cell-cell interactions. Therefore, any decrease in the number or function of these cells may lead to recurrent pregnancy loss (RPL). Thus, the objective of this study was to characterize Breg cell frequency and function in women who suffered from RPL in comparison with healthy non-pregnant and pregnant women (under twenty weeks of gestational age) as controls. Method: In this study, peripheral blood samples of women suffering from RPL (n=8), women with normal pregnancy under 20 weeks of gestational age (n=14), and healthy nonpregnant women (n=10) were collected. The frequency of Breg cells (CD19+CD24hiCD38hi) was measured by flow cytometry. The serum level of the IL-10 cytokine, as a marker of Breg cell function, was measured by ELISA. Results: The Percentage of Breg cells in women who suffered from RPL was significantly lower than that of women who had normal pregnancies (P=0.0016). The percentages of Breg cells in women who suffered from RPL were also significantly lower than in non-pregnant women (P=0.0001). Furthermore, no significant differences were observed in Breg cell percentages between normal pregnant and non-pregnant women. Evaluation of IL-10 concentration in the serum of women who had participated in this study showed no significant differences between the three groups. Conclusion: Based on our results, the number of Breg cells was significantly lower in RPL women than in healthy non-pregnant and normal-pregnant women, which shows the significance of these cells in the maintenance of normal pregnancy. However, we could not detect significant differences in the serum levels of IL-10, bringing to mind the notion that the beneficial and supportive function of these cells during pregnancy might be independent of IL-10 secretion. by these cells. Thus, screening of Breg cells in women with pregnancy complications, especially RPL, could be helpful for predicting a healthy pregnancy.