Expanded CD14⁺CD16⁺Monocyte Subpopulation in Patients with Acute and Chronic Infections Undergoing Hemodialysis

Abstract

Infections are frequent complications in end-stage renal failure patients undergoing hemodialysis (HD), and peripheral blood monocytes are important cells in host defense against infections. The majority of circulating monocytes express high levels of lipopolysaccharide receptor antigen CD14 and are negative for the immunoglobulin Fcγ receptor type III (CD16). We studied the occurrence of a minor subpopulation coexpressing low levels of CD14 together with CD16 in HD patients. In healthy controls CD14+ CD16+monocytes account for 8% ± 4% of CD14+ monocytes, with an absolute number of 29 ± 14 cells/μl. In stable HD patients the CD14+ CD16+ subpopulation was significantly elevated (14% ± 3%, or 66 ± 28 cells/μl), while the number of CD14++ monocytes (monocytes strongly positive for CD14) remained constant. In HD patients suffering from chronic infections a further rise in CD14+CD16+ monocytes was observed (128 ± 71 cells/μl;P < 0.01) such that this subpopulation constituted 24% of all blood monocytes. In contrast, numbers of CD14++cells did not change compared to those for stable HD patients, indicating that the CD14+ CD16+ monocyte subpopulation was selectively expanded. During acute infections the CD14+ CD16+ cell subpopulation always expanded. A whole-blood assay revealed that CD14+ CD16+monocytes exhibited a higher phagocytosis rate for Escherichia coli bacteria than CD14++ monocytes, underlining their role during host defense. In addition, CD14+CD16+ monocytes expressed higher levels of major histocompatibility complex (MHC) class II antigens (HLA-DR, -DP, and -DQ) and equal amounts of MHC class I antigens (HLA-ABC). Thus, CD14+ CD16+ cells constitute a potent phagocytosing and antigen-presenting monocyte subpopulation, which is expanded during acute and chronic infections commonly observed in chronic HD patients.

The CD14+ CD16+ blood monocytes: their role in infection and inflammation

“…Exposure of leukocytes to such membranes can induce an inflammatory response with increased cytokine production. Nockher and Scherberich [65] showed increased numbers of the CD14ϩ CD16ϩ monocytes in hemodialysis patients without signs of infection, and this was confirmed [66]. When following patients during hemodialysis, Nockher et al [67] also noted a preferential depletion of CD14ϩ CD16ϩ monocytes in blood early on within the first hour of hemodialysis with recovery of cell numbers within 4 h, and this was also seen in ref.…”

CD14 expression is increased on monocytes in patients with anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis and correlates with the expression of ANCA autoantigens

“…Indeed, our data demonstrate the expression of ANCA autoantigens in this cell population. In contrast to the data in AAV, the proportion of intermediate monocytes has been found to be increased in other inflammatory diseases, such as rheumatoid arthritis [15,16], and in patients on haemodialysis [36]. It is of interest that renal glomerular accumulation of CD16 high monocytes has been associated with lupus nephritis, and that this subset may be involved with the pathogenesis of glomerulonephritis in these patients [5].…”

Expression of CD14, CD16 and CD45RA on monocytes from periodontitis patients

“…with low CD14 (CD14 + CD16 + monocytes) increases in various inflammatory diseases, including septic shock (4) and bacteremia in dialysis patients (5), suggesting that bacteremia caused by periodontitis might affect the expression of CD14 and CD16 in periodontitis patients.…”