Effects of mannan-binding lectin on differentiation of Th17 cells

Abstract

Objective To investigate the effects of mannan-binding lectin (MBL) on the differentiation of Th17 cells (T helper cell 17, Th17). Methods CD4+ T cells were separated in vitro from fresh human cord blood by MACS (magnetic-activated cell sorting) separator. Anti-CD3 monoclonal antibody (McAb) and anti-CD28 McAb were used to stimulate CD4+ T cells with IL-6 and TGF-β1 as inducers. Then, these cells were treated with (MBL group) or without (control group) different concentrations of MBL. Percentages of Th17 cells in different groups were detected by fluorescence-activated cell sorting (FACS) after 72 hours of culturing. Quantitative real-time PCR (Q-PCR) was used to analyze the expression of RORγt (retinoid-related orphan receptor-γ-t) at mRNA level in both control and MBL groups. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the levels of IL-17A in supernatants of cell culture from different groups. FACS was used to detect the percentages of Th17 cells in MBL-/- and wild type (WT) mice. Results MBL could significantly reduce the percentage of Th17 cells after 72 hours of culturing as compared with the control group. Moreover, MBL could significantly down-regulate the expression of RORγt at mRNA level and decrease the expression of IL-17A. Results of animal experiments showed that the percentages of CD4+ RORγt+ Th17 cells in MBL-/- mice were significantly higher than those in WT mice. Conclusion MBL can inhibit the differentiation of CD4+ T cells to Th17 cells, which is induced by IL-6 and TGF-β1. Key words: Mannan-binding lectin (MBL); CD4+ T cell; Th17 cell; Induced differentiation