Small (CD14⁺/CD16⁺) Monocytes and Regular Monocytes in Human Blood

Abstract

Compared to the obvious phenotypic and functional heterogeneity of tissue macrophages, little information is available on subsets of blood monocytes. We have employed two-color immunofluorescence and flow cytometry for the definition of regular and small monocytes, the latter characterized by the low-density expression of CD 14 and the strong expression of the CD 16 (Fcy-RIII) antigen. These cells comprise 15% of the blood monocytes and they appear to be similar in phenotype to the alveolar macrophage. The CD14⁺/CD16⁺ small monocytes can perform phagocytosis and they produce reactive oxygen, while their capacity for cytokine production is strongly reduced when compared to regular monocytes. At this point it is still unclear as to whether the CD14+/CD16+ small monocytes comprise a specific level of activation or differentiation or a distinct sublineage of human blood monocytes.

Characterization of a CSF-induced proliferating subpopulation of human peripheral blood monocytes by surface marker expression and cytokine production

“…Immunomagnetic separation of CD16 ϩ and CD16 Ϫ subsets before culture demonstrated that purified CD16 Ϫ but not CD16 ϩ monocytes undergo DNA synthesis in response to either CSF (data not shown). Furthermore, in confirmation of published data [16,20], double surface labeling with CD14 and CD16 indicated that the CD16 ϩ cells tended to be low in CD14 intensity (data not shown). Elutriated human monocytes were cultured in 96-well polypropylene plates in 3% pNHS, 3% pNHS plus CSF-1 (5000 U/mL), or GM-CSF (10 ng/mL) for 5 days.…”

The detection of ADAM8 protein on cells of the human immune system and the demonstration of its expression on peripheral blood B cells, dendritic cells and monocyte subsets

“…Although CD14 + CD16 + cells represent only 10-15% of total blood monocytes (Ziegler-Heitbrock et al, 1991;Belge et al, 2002), they have previously been shown to have a much greater capacity for TNF-a production compared to CD14 2+ CD16 À monocytes (Belge et al, 2002). It remains to be seen, however, if such differential expression of ADAM8 would have any significant effect on monocyte subset functions.…”

Oxidative Stress, Lipid Rafts, and Macrophage Reprogramming

“…These populations consist of cells with CD16 surface expression but diminished CD14 expression (CD14ϩCD16ϩ) and one without CD16 expression (CD14ϩϩCD16Ϫ). The population of CD14ϩCD16ϩ mononuclear cells normally represents about 10% of the population in healthy adults (131). These CD14ϩCD16ϩ cells demonstrate proinflammatory features characterized by enhanced and altered liberation of proinflammatory factors, increased HLA-DR expression and little to no anti-inflammatory factors (132).…”