Effects of Mesenchymal Stem Cells on Proliferation and Immunomodulation of B Cells / 中山大学学报(医学科学版)

ABSTRACT

@#【Objective】To study the effect of mesenchymal stem cells（MSC）on proliferation and immunomodulation of B cells in vitro.【Methods】Bone marrow 30 mL from healthy donors was isolated by density gradient centrifugation. Isolated MSC were cultivated adherently with L- DMEM medium containing 10% fetal bovine serum（FBS）. Phenotype and differentiation capacity of MSC was detected after the sixth passage. Peripheral blood mononuclear cells（PBMC）of healthy donors were also obtained by density gradient centrifugation. CD19+ B cells were sorted by fluorescence activated and co-cultured with MSC（CD19+ B∶MSC = 5∶1）group. Stimulated by CpG+ CD40L，the proliferation of B cells of two groups were checked 96 hours after co-culture respectively. The CD19+CD5+ B cells percentage and its secretion of IL-10 were detected by FACS. The effects of CD19+ B cells on the proliferation of CD4+ T cells and the secretion of IFN-γ were continually observed. Anti-IL-10 was used to confirm the effect of B cells on proliferation and IFN-γ secretion of CD4+ T cells.【Results】MSC collected from healthy donors remained differentiation capacity. MSC derived from bone marrow expressed CD29，CD44，CD73，CD90，CD105，and CD166，but did not express CD45 and CD34. Compared with control group，the proportion of CD19+ B cells proliferation in co-cultured group was significantly increased after 3 days，meanwhile，the level of IFN-γ，which secreted by CD4+ T cells was significantly restrained. To make a further analysis of the subsets of CD19+ B cells，the percentage of CD5+ B cells in co-cultured group increased from（21.31±1.22）% to（31.27±0.92）%（P=0.014），and its IL-10 secretion increased from（1.09±0.08）% to（2.44±0.06）%（P<0.001）compared with control group. After anti-IL-10 was used，the B cells co-cultured with MSC showed a decreased capacity of inhibiting the proliferation and IFN-γ secretion of CD4+ T cells.【Conclusions】MSC could promote the proliferation of CD19+ B cells to inhibit the secretion of IFN-γ by CD4+ T cells，which may be related to the increasing expression of IL-10 by CD19+CD5+B cells.