The Effects Of Mannan-binding Lectin On The Differentiation And Function Of Regulatory T Cells

BackgroundMannan-binding lectin(MBL)is a protein that activates complement and promotes phagocytosis.Regulatory T cells(Tregs)are CD4+T cell subsets with immunoregulatory function in vivo.It is reported that the expression of surfactant protein A(SP-A),which is a C-type lectin family with MBL,can promote the expression of induced Tregs(iTregs).Does MBL also promote the regulation of iTregs expression? Does it affect the iTregs function? It is still unclear..Therefore,it is important to study the effect of MBL on Tregs induced differentiation and function,and to clarify the new role of MBL in acquired immunity.ObjectiveTo investigate the intervention of MBL on the number and function of regulatory T cells,and to provide a new experimental basis for the treatment of autoimmune diseases and inflammatory diseases.Methods1.Ficoll density centrifugation method: Human umbilical cord blood mononuclear cells(CBMCs)and human peripheral blood mononuclear cells(PBMCs)were isolated by Ficoll density centrifugation.2.Immunomagnetic beads sorting method: CD4+CD25-T cells were sorted from CBMCs by immunomagnetic beads sorting.CD4+CD25+T cells(i.e.,iTregs)were selected from MBL-induced CBMCs and MBL-induced CD4+CD25-T cell components using the same method.3.Flow cytometry(FCM)method: Flow cytometry was used to detect freshlyextracted CBMCs,and MBL-induced CBMCs and MBL-induced CD4+CD25-T cells at different concentrations,and the expression of Foxp3 was detected before and after induction.4.RT-PCR method: RT-PCR was used to collect CD4+CD25-T cells induced by different concentrations of MBL and CBMCs induced by different concentrations of MBL.The expression of Foxp3 mRNA was detected before and after induction.5.CCK-8 method: CCK-8 method to detect the effect of iTregs on the proliferation of PBMCs and CD4+CD25-T cells.Results1.Fresh cord blood mononuclear cells(CBMCs)expressed low Foxp3.2.MBL can significantly increase the proportion of CD4+CD25+Foxp3+T cells in CBMCs.3.MBL promotes differentiation of CD4+CD25-T cells into iTregs.4.MBL not only promotes high expression of Foxp3 mRNA in CBMCs,but also induces high expression of Foxp3 mRNA in CD4+CD25-T cells.5.iTregs not only inhibit the proliferation of PBMCs in a concentration-dependent manner,but also inhibit the proliferation of CD4+CD25-T cells in a concentrationdependent manner.6.Addition of MBL not only enhanced the inhibitory effect of iTregs on the proliferation of PBMCs,but also enhanced the inhibitory effect of iTregs on CD4+CD25-T cell proliferation.ConclusionMBL not only can synergistically promotes the differentiation of regulatory T cells,but also has a effect on Tregs inhibitory effect of T cell proliferation.