Comparison of Functional Competence of Umbilical Cord and Adult Peripheral Blood Dendritic Cells in Allogenic Mixed Leukocyte Reaction

Dendritic cells (DCs) are the most potent stimulators of primary T cell responses and play a key role in immune reactions after stem cell transplantation. Very little is known about the cord blood (CB) dendritic cells and their potential involvement in the low incidence and lower severity of acute graft-versus-host disease after CB transplantation. The aim of this study was the isolation of cord blood and peripheral blood dendritic cells and comparison of their functional competence and determination of their probable role in graft versus host disease after stem cell transplantation. In this study, fresh peripheral blood DCs (PBDCs) were enriched as HLA-DR+ cells, lacking the CD3, CD11b, CD14, CD16, CD19 and CD56, using immunomagnetic bead depletion. For cord blood dendritic cells (CBDCs) enrichment CD34+ and CD66b+ cells were needed to be depleted too. Immunomagnetically enriched PB/CB dendritic cells were co-cultured with adult T lymphocytes and cell proliferation was measured by 3H-thymidine incorporation. Results showed that CBDCs were significantly poor stimulators of the mixed leukocyte reaction as compared with PBDCs (P< 0.05). The demonstrated impairment of CBDCs function could be of importance in interpretation of the low incidence and milder severity of graft-versus-host disease (GVHD) in umbilical CB transplantation compared with peripheral blood or bone marrow stem cell transplantation.