Peripheral blood CD14high CD16+ monocytes are main producers of IL-10

Area of Science:

• Immunology
• Cell Biology

Background:

• Human peripheral blood monocytes (MO) are classified into CD14(high) CD16(-), CD14(high) CD16(+), and CD14(dim) CD16(+) subpopulations based on CD14 and CD16 expression.
• The CD14(dim) CD16(+) MO subset is recognized as pro-inflammatory, producing TNF-alpha with minimal IL-10 upon stimulation.
• Limited information exists regarding the functional characteristics of the CD14(high) CD16(+) MO subset.

Purpose of the Study:

• To investigate the surface marker expression, cytokine production, phagocytic capacity, and antigen-presenting function of CD16(+) monocyte subpopulations.
• To elucidate the distinct roles of CD14(high) CD16(+) and CD14(dim) CD16(+) monocyte subsets in immune responses.

Main Methods:

• Flow cytometry was used to analyze the surface expression of determinants like HLA-DR, CD86, CD54, CD64, CD11b, and TLR4 on monocyte subsets.
• Cytokine production (TNF-alpha, IL-10) was measured following lipopolysaccharide (LPS) stimulation.
• Phagocytosis and antigen presentation assays were performed on isolated monocyte subpopulations.

Main Results:

• Both CD16(+) monocyte subpopulations displayed higher HLA-DR, CD86, and CD54 expression and lower CD64 expression compared to the CD14(high) CD16(-) population.
• The CD14(high) CD16(+) subset showed increased CD11b and TLR4 expression.
• CD14(high) CD16(+) MO exhibited enhanced phagocytic activity but reduced antigen presentation compared to CD14(dim) CD16(+) MO.
• LPS-stimulated CD14(high) CD16(+) MO produced significantly more IL-10 than CD14(dim) CD16(+) and CD14(high) CD16(-) MO.

Conclusions:

• Human peripheral blood CD16(+) monocytes are functionally heterogeneous, comprising distinct CD14(dim) CD16(+) and CD14(high) CD16(+) subsets.
• The CD14(dim) CD16(+) subset is confirmed as pro-inflammatory.
• The CD14(high) CD16(+) subset demonstrates anti-inflammatory potential, primarily through IL-10 production.