IgG and complement receptor expression in children treated by peritoneal dialysis

Children treated by peritoneal dialysis (PD) are at increased risk of infections. IgG receptors (Fc gamma Rs) and complement receptors (CRs) on white blood cells (WBCs) are important for the phagocytic process. We have investigated Fc gamma R and CR expression on monocytes, macrophages and neutrophils in blood and in peritoneal dialysis effluent (PDE) of 39 PD children. WBCs were isolated from blood and PDE, labelled with FITC-conjugated CD16 (Fc gamma RIII), CD32 (Fc gamma RII), CD64 (Fc gamma RI), CD11b (CR3) and CD35 (CR1) monoclonal antibodies, and analysed by flow cytometry. Peritoneal cells had lower percentages of Fc gamma R-positive or CR-positive cells than blood. On the other hand, the receptor number per cell [mean fluorescence intensity (MFI)] was higher on peritoneal macrophages and neutrophils than blood, except for CD16. The Fc gamma R and CR expression in blood and dialysate did not change significantly during the first year of PD treatment. During a peritonitis episode the MFI of all receptors in blood increased only on monocytes, with the exception of CD32. The percentages of Fc gamma R-positive and CR-positive macrophages and neutrophils in the PDE increased, whereas the MFI did not increase consistently. Peritoneal cells of PD children showed a lower percentage of Fc gamma R-positive and CR-positive neutrophils and macrophages, combined with an increased MFI, indicating a state of activation. Blood and peritoneal cells are capable of up-regulating the receptor expression during peritonitis but probably not to a maximum level.