Impaired function of macrophage Fc gamma receptors and bacterial infection in alcoholic cirrhosis.

BACKGROUND: Bacterial infection is a frequent and often fatal complication in patients with cirrhosis. Macrophages play an important part in the host defense against infection because their Fc gamma receptors recognize antibody-coated bacteria.
METHODS: We prospectively studied macrophage Fc gamma-receptor function in vivo and in vitro in 49 patients with alcoholic cirrhosis, 10 alcoholics without cirrhosis, and 20 normal volunteers.
RESULTS: The clearance of IgG-sensitized autologous red cells was decreased in 37 of the 49 patients with cirrhosis but in none of the subjects without cirrhosis. In the 49 patients clearance was inhibited by a mean (+/- SE) of 47 +/- 3 percent at 1 hour and 53 +/- 3 percent at 1 1/2 hours, as compared with the clearance in the normal controls (P < 0.001). The impairment of macrophage Fc gamma-receptor-dependent clearance correlated with the degree of liver insufficiency but not with age, sex, nutritional status, HLA haplotype, or the presence of circulating immune complexes. The clearance of unsensitized and heat-altered autologous erythrocytes was normal. In vitro recognition of IgG-sensitized red cells by monocytes from the patients was not significantly decreased. During a two-year follow-up period, 11 patients had severe bacterial infections, and in 4 they were fatal. The mean clearance of IgG-sensitized red cells in these 11 patients (half-time, 126.2 +/- 22 hours) was significantly impaired, as compared with that in the 38 patients without severe infection (half-time, 32.2 +/- 18 hours, P < 0.001).
CONCLUSIONS: The function of macrophage Fc gamma receptors is impaired in patients with alcoholic cirrhosis, and this impairment probably contributes to the high incidence of bacterial infections among such patients.