Macrophage serum markers in pneumococcal bacteremia: Prediction of survival by soluble CD163

OBJECTIVE:Soluble CD163 (sCD163) is a new macrophage-specific serum marker. This study investigated sCD163 and other markers of macrophage activation (neopterin, ferritin, transcobalamin, and soluble urokinase plasminogen activator receptor [suPAR]) as prognostic factors in patients with pneumococcal bacteremia. DESIGN:Observational cohort study. SETTING:Five university hospitals in Denmark. PATIENTS:A total of 133 patients with Streptococcus pneumoniae bacteremia (positive blood culture) and 133 age- and gender-matched controls. INTERVENTIONS:Samples were collected for biochemical analyses at the time of first positive blood culture. MEASUREMENTS AND MAIN RESULTS:sCD163 was highly correlated with other macrophage markers and was significantly elevated (median [25–75 percentiles], 4.6 mg/L [2.8–8.9]) compared with healthy controls (2.7 mg/L [2.1–3.3], p < .0001). Increased levels were observed in patients who needed intensive care (hemodialysis, p = .0011; hypotension, p = .0014; mechanical ventilation, p = .0019). Significantly lower levels of sCD163, ferritin, transcobalamin, and suPAR (but not C-reactive protein) were measured in patients ≥75 yrs. In patients