Identification of both myeloid CD11c(+) and lymphoid CD11c(-) dendritic cell subsets in cord blood

Dendritic cells (DCs) are the most potent antigen-presenting cells describe d to date. In human peripheral blood, both myeloid and lymphoid subsets of DCs have been identified. In contrast, cord blood (CB) DCs have recently be en described as being exclusively of the immature CD11c(-) lymphoid DC subs et. Using an alternative method of enrichment, based on a negative selectio n system, both lymphoid (HLA-DR+ CD123(+++) CD11c(-) CD33(-)) and myeloid ( HLA-DR++ CD123(+) CD11c(+) CD33(+)) DCs were identified in CB. Although the majority of CB DCs showed a lymphoid phenotype, a significant number of CD 11c(+) myeloid DCs (25.6% +/- 14.5%, n = 13) were also present. Other marke rs, such as CD80 and CD83, were negative in both subsets. Analyses of the a llostimulatory capacity of both subsets showed that freshly isolated CB lym phoid DCs failed to induce a potent allostimulation of naive CB T cells. Th ese features are therefore consistent with previous work reporting an immat ure phenotype for lymphoid DCs in adult blood. The significance of the inve rted CD11c(+)/CD11c(-) ratio observed in CB DCs (1:3) with respect to adult blood DCs (3:1) remains to be explained.