Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Characterization of human blood dendritic cell subsets

Abstract

Dendritic cells (DC) are key antigen presenting cells for stimulating immune responses and they are now being investigated in clinical settings. Although defined as lineage negative (Lin-) HLA-DR+ cells, significant heterogeneity in these preparations is apparent, particularly in regard to the inclusion or exclusion of CD14+, CD16+ and CD2+ cells. This study used flow cytometry and a panel of monoclonal antibodies (mAb), including reagents from the 7th Leucocyte Differentiation Antigen Workshop, to define the cellular composition of two standardised peripheral blood mononuclear cell (PBMC) derived Lin-HLA-DR+ preparations. Lin- cells were prepared from PBMC by depletion with CD3, CD14, CD19, CD11b and either CD16 or CD56 mAb. Analysis of the CD16 replete preparations divided the Lin-HLA-DR+ population into 5 non overlapping subsets: CD123 (mean=18.3 ± 1SD=9.7%), CD1b/c (18.6 ± 7.6%), CD16 (49.6 ± 8.5%) BDCA-3 (2.7 ± 1.4%) and CD34 (5.0 ± 2.4%). The 5 subsets were shown to have distinct phenotypes when compared with each other, monocytes and monocyte derived DC. The ILT molecular family, C type lectins, co-stimulatory molecules and differentiation/activation antigens were also expressed differentially on the five Lin-HLA-DR+ subsets, monocytes and Mo-DC. The poor viability of CD123+ DC in vitro was confirmed but the CD16+ CD11c+ DC subset also survived poorly. Finally, the individual subsets used as stimulators in allogeneic MLRs were ranked by their allostimulatory capacity as CD1b/c >CD16 >BDCA-3 >CD123 >CD34. These data provide an opportunity to standardise the DC populations used for future molecular, functional and possibly even therapeutic studies.