ABSTRACT
Objective To study the immunoregulatory effects of bone marrow mesenchymal stem cells (MSC) on allogeneic peripheral B lymphocytes in vitro. Methods MSCs were isolated and cultured from bone marrow by gradient centrifugation. Mononuclear cells were isolated routinely from peripheral blood, then monocytes were eliminated by L-leucine methy ester method. Remained T lymphocytes were eliminated by AET-SRBC rosette method. The action of MSCs and its supernatant on B lymphocytes proliferation in the presence of anti-human IgM goat antibodies (anti-IgM) was investigated by MTT. The IgG, IgM in the supernatant were detected by ELISA. The percent of apoptosis B lymphocytes, co-cultured with MSCs for 24 or 48h, was assayed by FACS. Results MSCs and its supernatant inhibited B lymphocytes proliferation and Ig secretion. The inhibitory effect depended on the amount of MSCs and condition of its supernatant. The date of FACS indicated that the apoptosis ratio of B lymphocytes, co-cultured with MSCs for different times, were non-significant. The inhibitory effect of MSCs on B lymphocytes was temporary and reversible. Conclusion MSCs have immunoregulatory effects on B lymphocytes, and its mechanisms are complex, not only correlating with the concentration of MSCs but also the action between cells and the secretory cytokine of MSCs.