Mannose‐binding lectin does not act as an acute‐phase reactant in adults with community‐acquired pneumococcal pneumonia

Summary The objective of this work was to study the role of mannose‐binding lectin (MBL) and C‐reactive protein (CRP) in pneumococcal pneumonia, to determine whether MBL acts as an acute‐phase reactant and whether the severity of the disease correlates with MBL levels. The study comprised 100 patients with pneumococcal pneumonia. The pneumonia severity score was calculated and graded into a risk class of mortality (Fine scale). The MBL genotypes and the levels of MBL and CRP at the acute and recovery phases were determined. Fifty patients with the wild‐type MBL genotype showed higher MBL levels in each phase ( P  < 0·001) and an increased risk to developing bacteraemia, odds ratio (OR) 2·74, 95% confidence interval (CI) 1·01–7·52) ( P  = 0·02), but this did not correlate with the pneumonia severity class. CRP levels in the acute phase, 79·53 mg/l [standard deviation (s.d.) 106·93], were higher in the subjects with positive blood cultures ( P  = 0·003), and remained higher [20·12 mg/l (s.d. 31·90)] in the group of patients with an underlying disease ( P  = 0·01). No correlation was observed between the levels of MBL and CRP in each phase, or with the pneumonia severity score. We cannot conclude that MBL acts uniformly as an acute‐phase reactant in pneumococcal pneumonia. MBL levels do not correlate well with the severity of the pneumonia. The risk of developing bacteraemia could be enhanced in individuals with the wild‐type MBL genotype.