Characterization of myeloid and lymphoid subsets in dendritic cells derived from cord blood and adult blood

Dendritic cells (DC) are antigen presenting cells that play a critical role in T cell dependent immune responses. Two distinct DC subsets have been identified based on surface phenotype, cytokine requirements, and immunologic function. Myeloid DCs are GM-CSF dependent and express CD11c+ and CD45RO+. Lymphoid DCs are IL-3 dependent and express CD45RA+ and CD123+. Myeloid DCs initiate Th1 immune responses, whereas lymphoid DCs regulate Th2 responses. We sought to characterize these subsets in freshly isolated CD4+ DCs and in monocyte-derived DCs from cord and adult blood. CD4+ DCs were isolated from blood mononuclear cells using antibody-linked magnetic microbeads, first to deplete B cells, T cells, monocytes and NK cells, then to select for CD4+ DCs. Monocytes were isolated from blood by positive selection using anti-CD14 linked magnetic microbeads. Monocytes were cultured in GM-CSF and IL-4 for 7 days. TNF-α was added on day 5. Surface phenotypes of CD4+ DCs and monocyte-derived DCs were evaluated by flow cytometry for lineage, MHC, adhesions, co-stimulatory, and cytokine receptor molecules. We found that CD4+ DCs included both subsets with a predominance of lymphoid DCs. In contrast, monocyte derived DCs exhibited a myeloid surface phenotype (CD11c+ and CD45RO+). No differences in DC subsets were observed between cord blood and adult blood. We conclude that distinct DC subsets can be generated from blood based upon the method of isolation. We speculate that DC-based strategies might be feasible for the prevention and treatment of infectious diseases in newborn infants.