ABSTRACT
BACKGROUND: Bone marrow mesenchymal stem cells (MSC) inhibit the immune response of lymphocytes to specific antigens and dendritic cells (DC) are professional antigen- presenting cells whose function is to present antigen to naive T-lymphocytes with high efficiency and play a central role in the regulation of immune response. We studied the effects of MSC on DC to evaluate the relationship between MSC and DC in transplantation immunology. METHODS: MSC were expanded from the bone marrow and DC were cultured from peripheral blood mononuclear cells (PBMNC) of 6 myelogenous leukemia after achieving complete response. Responder cells isolated from PBMNC and lysates of autologous leukemic cells are used as tumor antigen. The effect of MSC on the DC was analyzed by immunophenotype properties of DC and by proliferative capacity and the amount of cytokine production with activated PBMNC against the allogeneic lymphocytes. Also, cytotoxicity tests against leukemic cells studied to evaluate the immunologic effect of MSC on the DC. RESULTS: MSC inhibit the CD83 and HLA- class II molecules of antigen-loaded DC. The proliferative capacity and the amount of INF-gamma production of lymphocytes to allogeneic lymphocytes were decreased in DC co-cultured with MSC. Also the cytotoxic activity of lymphocytes against leukemic cells was decreased in DC co-cultured with MSC. CONCLUSION: MSC inhibit the activation and immune response of DC induced by allogeneic or tumor antigen.