CX₃CR1 expression on peripheral monocytes from different clinical groups. Whole blood from HC (n = 10); patients with HUS (n = 19), UC (n = 14), and IC (n = 10) was stained with PECy5-labeled anti-CD14, PE-labeled anti-CD16, and FITC-labeled anti-CX₃CR1 and analyzed by flow cytometry as described in “Patients, materials, and methods.” Mo subpopulations were defined according to their CD14 expression, and that of CX₃CR1 and CD16 were depicted. (A) Representative dotplots from 1 child within each clinical group showing CX₃CR1 and CD16 expression on CD14⁺ Mo's. Dot plot quadrants are defined as: CX₃CR1⁺/CD16⁺, top right; CX₃CR1⁻/CD16⁺, top right; and CX₃CR1⁺/CD16⁻, bottom right. The percentages of the different subpopulations are shown within each quadrant. (B) According to CX₃CR1 and CD16 membrane expression, 4 subpopulations were defined. Each bar represents the mean ± SEM of the percentage of cells for each subpopulation among HC (□); patients with HUS (▪); UC (▧), and IC (). (C) Each bar represents the mean ± SEM of the absolute number of cells for each Mo subset within the different clinical groups. *P < .05; **P < .01; ***P < .005 statistically different compared with HC and UC; #P < .05 compared with HUS.