["Macrophage activation plays a key pathogenic role in experimental non-alcoholic fatty liver disease (NAFLD) and contributes to the progression of steatohepatitis (NASH) and fibrosis. We studied macrophage activation in human NAFLD by measuring soluble (s)CD163, a specific macrophage activation marker, hypothesizing that sCD163 would be associated with the patients' morphological disease grade. Furthermore, we investigated an association between sCD163 and the apoptosis marker cytokeratin-18 (CK-18) to explore a link between macrophage activation and apoptosis.", 'sCD163 associations with biochemical and histological measures of NAFLD were investigated in two independent cohorts of 157 Australian and 174 Italian NAFLD patients, with liver biopsies graded for NAFLD severity, steatosis and fibrosis. sCD163 and CK-18 were measured by enzyme-linked immunosorbent assay.', "In both cohorts sCD163 increased in parallel with the patients' morphological disease grading, being independently associated with the Kleiner fibrosis score (P < 0.001). A high sCD163 predicted advanced fibrosis {F ≥ 3; Australian cohort: area under receiver-operating characteristics curve 0.77 [95% confidence interval (CI): 0.76-0.87], Italian cohort: 0.80 (95% CI: 0.72-0.88)}. In both groups, sCD163 was independently associated with CK-18 (P < 0.001)."] Is the macrophage activation marker sCD163 associated with morphological disease stages in patients with non-alcoholic fatty liver disease?