Expanded CD141 CD161 Monocyte Subpopulation in Patients with Acute and Chronic Infections Undergoing Hemodialysis

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 immuno-globulin Fcg 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 CD141 CD161 monocytes account for 8 % 6 4 % of CD141 monocytes, with an absolute number of 29 6 14 cells/ml. In stable HD patients the CD141 CD161 subpopulation was significantly elevated (14 % 6 3%, or 66 6 28 cells/ml), while the number of CD1411 monocytes (monocytes strongly positive for CD14) remained constant. In HD patients suffering from chronic infections a further rise in CD141 CD161 monocytes was observed (128 6 71 cells/ml; P < 0.01) such that this subpopulation constituted 24 % of all blood monocytes. In contrast, numbers of CD1411 cells did not change compared to those for stable HD patients, indicating that the CD141 CD161 monocyte subpopulation was selectively expanded. During acute infections the CD141 CD161 cell subpopulation always expanded. A whole-blood assay revealed that CD141 CD161 monocytes exhibited a higher phagocytosis rate for Escherichia coli bacteria than CD1411 monocytes, underlining their role during host defense. In addition, CD141 CD161 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, CD141 CD161 cells constitut