Serum Ficolin-2 in Hospitalised Patients with Community-Acquired Pneumonia

Mannose binding lectin (MBL) and ficolins contribute to host defence through activation of the lectin pathway of complement. In this study, serum levels of ficolin-2 and MBL were determined in 276 patients with community-acquired pneumonia (CAP). MBL deficiency and ficolin-2 insufficiency were defined using previously validated cut-offs. No differences were observed in MBL or ficolin-2 between patients and controls. MBL-deficient patients (<500 ng/ml) were not at higher risk of 30-day mortality odds ratio (OR) 0.97 (0.38–2.48,p = 0.9) or a composite outcome of mortality, mechanical ventilation, vasopressor support (MV/VS) or complications OR 0.89 (0.44–1.77, p = 0.9). Although no significant relationship between ficolin-2 insufficiency and outcome was observed, very low ficolin-2 levels (<1,200 ng/ml) were associated with an OR 1.23 (0.15–10.1), p = 0.6 for 30-day mortality, 3.05 (0.61–15.2, p = 0.2) for MV/VS and OR 2.05 (0.52–8.1, p = 0.2) for the composite outcome. Low serum levels of MBL and ficolin-2 are not associated with CAP susceptibility. The high frequency of ficolin-2 insufficiency in patients with severe CAP would justify a larger investigation of ficolin-2 as a modifier of CAP severity.