Monocyte-Related Determinants of Inflammation in Patients on Peritoneal Dialysis

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Abstract
Aims: We studied markers of monocyte activation, i.e., the cell surface expression of CD11b and CD62L, and the serum concentrations of monocyte chemotactic protein 1 (MCP-1; a monocyte-specific chemoattractant) and soluble vascular cell adhesion molecule 1 (sVCAM-1; an adhesion molecule involved in monocyte recruitment) in 20 patients on peritoneal dialysis (PD), in 25 patients with chronic renal insufficiency, and in 27 healthy subjects. Results: Monocytes obtained from the peripheral blood of PD patients had a significantly higher expression of CD62L (p = 0.02) as compared with monocytes from healthy subjects and a lower CD11b/CD18 expression as compared with monocytes collected from healthy subjects (p < 0.001) and from patients with renal insufficiency (p < 0.001). Monocytes from PD patients had, however, the capacity to increase the expression of CD11b following stimulation with a potent chemotactic factor. The serum concentrations of MCP-1 and sVCAM-1 were higher in PD patients (575 ± 51 and 1,517 ± 89 ng/ml) than in healthy subjects (225 ± 17 and 668 ± 64 ng/ml, respectively; p < 0.001 for both comparisons). There was a correlation between the levels of sVCAM-1 and MCP-1 (r = 0.48, p < 0.05) in patients on PD, but neither correlated with the monocyte expression of CD11b/CD18 or CD62L. The concentration of C-reactive protein was higher in patients on PD as compared with healthy subjects and correlated significantly with the concentration of sVCAM-1 (r = 0.63, p < 0.01). Conclusions: Monocytes in the peripheral circulation of patients on PD have a CD62Lhigh/CD11blow phenotype, indicating that they have not undergone complete differentiation. Patients also have an increase in the systemic chemotactic activity for monocytes in combination with increased levels of sVCAM-1 and C-reactive protein. These inflammatory aberrations may play a pathophysiological role in the response to inflammatory and infectious diseases in patients on PD.