[Immunoregulatory effect of mesenchymal stem cells on active T lymphocytes].

This study was purposed to explore the immunoregulatory effects of human bone marrow mesenchymal stem cells (MSCs) on active T lymphocytes in vitro and the new strategy to prevent graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Mononuclear cells from human peripheral blood cells were isolated and cultured in the presence of phytohemagglutinin (PHA) (final concentration was 10 microg/ml) for different times. The ability of T lymphocyte proliferation and activation was measured by (3)H-Thyramine incorporation. The expressions of CD3(+)CD4(+), CD3(+)CD8(+), CD4(+)CD25(+) and CD4(+)CD152(+) on T cells were detected by FCM after coculture for 72 hours. Experiment was divided into 4 groups: A group as control (no added MSCs), B group (actived T cells + 2 x 10(4) MSCs), C group (actived T cells + 4 x 10(4) MSCs), D group (actived T cells + 8 x 10(4) MSCs). The results showed that the ability of T lymphocyte proliferation in the same PHA concentration increased with prolonging of time. ability of T lymphocyte proliferation was strongest when culturing for 48 hours (p < 0.01); the expressions of CD44, CD105, CD29 and FIK1 of MSCs were positive, expressions of CD33, CD34, CD45 and HLA-DR were negative. MSCs inhibited T lymphocyte proliferation and the inhibitory effect depended on the amount of MSCs. CD3(+)CD8(+), CD4(+)CD25(+) and CD4(+)CD152(+) T cells cocultured with MSCs increased obviously and CD3(+)CD4(+) expression significantly decreased, as compared with control group (p < 0.01). It is concluded that the MSCs inhibit T lymphocyte proliferation induced by mitogen (PHA), and perform their immunosuppressive function by up-regulation of CD3(+)CD8(+), CD4(+)CD25(+) and CD4(+)CD152(+) expressions and down-regulation of CD3(+)CD4(+) expression.