Peripheral Blood CD14high CD16+ Monocytes are Main Producers of IL‐10

Based on CD14 and CD16 expression, human peripheral blood monocytes (MO) can be divided into a major CD14high CD16− population and two minor CD14high CD16+ and CD14dim CD16+ subpopulations. CD14dim CD16+ MO are well characterized and regarded as pro-inflammatory because upon stimulation produce TNF-α but little, if any, IL-10. By contrast, little is known about CD14high CD16+ MO. We investigated the surface expression of selected determinants by CD16+ MO subpopulations, cytokine production, phagocytosis and antigen presentation. We found that both CD16+ subpopulations had a higher expression of HLA-DR, CD86, CD54 and a lower expression of CD64 than CD14high CD16− population. In addition, CD14high CD16+ MO showed a higher expression of CD11b and TLR4 than CD14dim CD16+ and CD14high CD16− subpopulations. CD14high CD16+ MO exhibited an increased phagocytic activity and a decreased antigen presentation in comparison with CD14dim CD16+. As expected, lipopolysaccharide (LPS)-stimulated CD14dim CD16+ MO produced TNF-α but little IL-10. By contrast, LPS-stimulated CD14high CD16+ subpopulation produced significantly more IL-10 than CD14dim CD16+ and CD14high CD16− MO. In conclusion, our data show that human peripheral blood CD16+ MO are heterogeneous in function and consist of two subpopulations: CD14dim CD16+ pro-inflammatory and CD14high CD16+ with anti-inflammatory potential.