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

Abstract

Based on CD14 and CD16 expression, human peripheral blood monocytes (MO) can be divided into a major CD14^high CD16⁻ population and two minor CD14^high CD16⁺ and CD14^dim CD16⁺ subpopulations. CD14^dim 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 CD14^high 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 CD14^high CD16⁻ population. In addition, CD14^high CD16⁺ MO showed a higher expression of CD11b and TLR4 than CD14^dim CD16⁺ and CD14^high CD16⁻ subpopulations. CD14^high CD16⁺ MO exhibited an increased phagocytic activity and a decreased antigen presentation in comparison with CD14^dim CD16⁺. As expected, lipopolysaccharide (LPS)-stimulated CD14^dim CD16⁺ MO produced TNF-α but little IL-10. By contrast, LPS-stimulated CD14^high CD16⁺ subpopulation produced significantly more IL-10 than CD14^dim CD16⁺ and CD14^high CD16⁻ MO. In conclusion, our data show that human peripheral blood CD16⁺ MO are heterogeneous in function and consist of two subpopulations: CD14^dim CD16⁺ pro-inflammatory and CD14^high CD16⁺ with anti-inflammatory potential.