Effect of placental protein 14 on the proliferation and differentiation of B cells

Objective To investigate the effect and mechanism of placental protein 14 on the proliferation and differentiation of B cells. Methods The lymphocyte of human peripheral blood was separated by gradient centrifugation. Flow cytometry was used to detect the proportion of CD4+CXCR5+ follicular helper T cells (Tfh cells), CD4+CXCR5+Foxp3+ follicular regulatory T cells (Tfr cells), CD3-CD19+B cells and CD3-CD38+ plasma cells. ELISA method was used to detect the concentration of IL-21, IL-10 and TGF-beta in the supernatant, and the co-culture of cells was performed by Transwell chamber; t test was used for comparison between groups. Results The proportion of Tfh cells and Tfr cells in the control group was (2.52±0.16)% and (1.26±0.24)%, respectively, and that of the placental protein 14 groups were (0.84±0.09)% and (4.64±0.68)%, respectively. There was a significant difference between the two groups (t=9.150, P=0.000 8 and t=4.669, P=0.009 5). Pplacental protein 14 could further inhibit the secretion of IL-21 (t=5.086, P=0.007 1), and promote the increase of IL-10 and TGF-β concentration (t=3.599, P=0.022 8 and t=6.651, P=0.002 7). The percentage of B cells and plasma cells in the placental protein 14 group were (4.87±0.20)% and (5.41±0.54)%, which were significantly different from those in the Tfh cell group (t=4.997, P=0.007 5; t=5.110, P=0.006 9). Conclusion Placental protein 14 can inhibit the proliferation of B cells and differentiate into plasma cells by inhibiting the differentiation of Tfh cells and increasing the proportion of Tfr cells. Key words: Arthritis, rheumatoid; B cells; Placental proteins; T-lymphocytes, regulatory; T-lymphocytes, helper-inducer