[The immunoregulatory function of bone marrow mesenchymal stem cells on allogeneic B lymphocytes]

To investigate the immunoregulatory function of bone marrow mesenchymal stem cells (MSCs) on allogeneic B lymphocytes in vitro, and explore its possible mechanisms.

Human MSCs were isolated from bone marrow and expanded in vitro. The purity of MSCs were identified with the spindle fibroblastic morphology by micro-photograph and the phenotype by flow cytometry. MSCs were irradiated with 20 Gy of gamma ray to abolish proliferative capacity. The change of activated B cells proliferative capability and apoptosis with or without MSCs were examined. The effect of MSCs on activated B cells proliferation was compared between transwell cultures and non-transwell cultures. The IgG, IgA and IgM productions of B cells and the immune molecules expression with or without MSCs were assessed. RESULTS (1) MSCs could not induce the proliferation of B lymphocytes, but could suppress LPS activated B lymphocytes proliferation. (2) With the number of MSCs increased, a dose-dependent inhibitory effect was observed in B cell proliferation. MSCs could not induce B cells apoptosis. The activated B cells proliferation with MSCs in transwell culture was decreased, suggesting that MSCs inhibition of B cells might be mediated both by cell-to-cell contact and soluble factors. (3) MSCs suppressed the IgG, IgA and IgM production of B cells, but not suppressed the immune molecules HLA-DR, CD40, CD80 and CD86 expression.

Bone marrow MSCs can suppress allogeneic B lymphocytes proliferation and its secretion in vitro.