Acquired C3 deficiency in patients with alcoholic cirrhosis predisposes to infection and increased mortality.

BACKGROUND Acquired deficiencies of certain complement proteins and impaired opsonisation activity have been implicated in the pathogenesis of the increased susceptibility to infections of patients with alcoholic cirrhosis. METHODS Serum concentrations of C3 and C4, plasma concentrations of C3bc, C9, and the terminal C5b-9 complement complex (TCC), and haemolytic complement activity (classic and alternative pathway) of serum, and serum opsonic activity were determined in 46 patients with compensated alcoholic cirrhosis, 31 who were decompensated, and in 15 healthy subjects. After 19 months (median) the investigated variables were analysed for their use in prognosis of recurrent infections and survival. RESULTS C3 and C4 concentrations and the haemolytic complement activity of the alternative pathway were decreased in decompensated cirrhotic patients compared with controls (p < 0.01). Univariate analysis (log rank test) showed that low concentrations (< or = lower quartile) of C3 (p < 0.001) and C3bc (p < 0.05), haemolytic complement activity of the alternative pathway (p < 0.01) and classic pathway (p < 0.05), and decompensated cirrhosis (p < 0.001) were associated with an increased risk of infection and increased mortality. Multivariate (Cox) analysis showed that low C3 concentrations and decompensation of cirrhosis were significant predictors of infections and mortality (p < 0.02). CONCLUSIONS Low serum C3 concentrations and decreased haemolytic complement function predisposes to infection and increased mortality in patients with alcoholic cirrhosis.