CD14+CD16++ cells derivedin vitro from peripheral blood monocytes exhibit phenotypic and functional dendritic cell-like characteristics

We previously reported an increased percentage of CD14+CD16++ monocytes in the peripheral blood of HIV-infected patients but the physiopathological role of this monocyte subset remains unclear. Cells with a CD14+CD16++ phenotype may be obtained in vitro by culturing human peripheral blood monocytes in the presence of GM-CSF, IL-4 and IL-10. In the present study, we compared the phenotypic and functional characteristics of monocytes-derived CD14+CD16++ cells with those of macrophages and dendritic cells. We show that the CD14+CD16++ cells express dendritic cell markers: CD40, CD80, CD86, HLA-DR, CD11b, CD11c, CD18, CD1a, and CD83. Using RNase protection assay, we demonstrate that CD14+CD16++ cell subset expresses a low ratio of IL-1beta/IL-1ra mRNA and expresses IL-6, MIP-1alpha, MIP-1beta, MCP-1, IL-8, RANTES and I-309 transcripts, similar to dendritic cells. CD14+CD16++ cells produce IL-12, MCP-1 and IL-8, as assessed by flow cytometry. Moreover, CD14+CD16++ cells pulsed with different recall antigens induce a potent autologous T cell proliferation. Altogether, these results provide evidence that CD14+CD16++ cells differentiated in vitro from peripheral blood monocytes exhibit dendritic cell characteristics.