In vitro effects of ethanol on the phagocytic and microbial killing activities of normal human monocytes and monocyte-derived macrophages.

Human blood monocytes were cultured within the wells of chamber slides in growth medium to which 0, 1, 2, or 3 mg ethanol per ml was added at the start of the culture. After incubation for 1 h, 1 day and 7 days, their ability to phagocytoze IgG-sensitized red cells and to phagocytoze and kill non-opsonized Candida albicans was assessed. In all alcohol-containing wells, the concentration of alcohol in the growth medium fell progressively, reaching negligible values after 3 days. When compared with control cells, monocytes incubated with 1, 2 or 3 mg ethanol/mg for 1 h showed impaired phagocytosis of IgG-sensitized RBC and non-opsonized C. albicans and those incubated with 1 or 2 mg ethanol/ml for 1 h showed impaired killing of Candida. After incubation for 7 days, the monocyte-derived macrophages in wells initially containing 1, 2 or 3 mg ethanol/ml showed increased phagocytic activity towards C. albicans but not towards sensitized RBC. In addition, in 4 of 5 experiments, the percentage of phagocytozed organisms killed was increased in wells initially containing 1 mg ethanol/ml. The results support the view that the susceptibility of chronic alcoholics to certain infections may be partly dependent on an ethanol-induced depression of the phagocytic and killing functions of macrophages. They also suggest that a few days after a brief period of exposure to ethanol there may be stimulation of certain but not all effector functions of macrophages.