Plasma long pentraxin 3 (PTX3) concentration is a novel marker of disease activity in patients with community-acquired pneumonia

Background: Long pentraxin 3 (PTX3) is an acute-phase protein secreted by various cells, including leukocytes and endothelial cells. Like C-reactive protein (CRP), it belongs to the pentraxin superfamily. The aim of this study was to investigate the differential changes in plasma levels of PTX3 between before and after antibiotic treatment in hospitalized adult patients with community-acquired pneumonia (CAP). Methods: Plasma PTX3 levels were measured in 61 adult patients with CAP and 60 healthy controls using a commercial enzyme-linked immunosorbent assay (ELISA). Upon initial hospitalization, APACHE II, CURB-65, and pneumonia severity index (PSI) scores were determined to assess CAP severity in patients. Results: The results showed a decline in the number of white blood cells (WBCs) and neutrophils, and decreases in the concentrations of CRP and PTX3 observed after antibiotic treatment. The plasma concentration of PTX3, but not CRP, was correlated with the severity of CAP based on the PSI (r = 0.290, p = 0.023), CURB-65 (r = 0.312, p = 0.015), and APACHE II scores (r = 0.427, p = 0.001). The PTX3 level also exhibited a significant correlation with the length of hospital stay (r = 0.500, p