Berit Mørland

Decreased Fc-receptor binding in human monocytes exposed to ethanol in vitro

Human blood monocytes were incubated with or without ethanol (14 mM-220 mM, initial concentration) in non-sealed wells in an atmosphere of 5% CO2 in air for various time periods. The actual ethanol concentration was assayed in the media at the beginning and at the end of each incubation period. No change in ethanol content was found after 5 or 15 min incubation, while a reduction to about 70% of the initial concentration was observed after 6 hr incubation. Binding of IgG-opsonized particles to the Fc-receptors was tested after ethanol exposure of the cells. An initial concentration of 14 or 28 mM ethanol caused no difference from controls, neither did incubation in 55 mM ethanol for 5 min. Monocyte incubated in 55 mM ethanol for 15 min showed reduced binding of particles, and further reduction was obtained by increasing the ethanol concentration. Six hr incubation in 55 mM ethanol caused no further reduction in binding capacity. Reduced binding of test particles to Fc-receptors after ethanol incubation was demonstrated with variable amounts of test particles, as well as variable length of the binding assay period. There was no change in viability, morphology or spreading ability of the monocytes after ethanol treatment.

Different effects of ethanol on particle phagocytosis via different receptors in human monocytes

Endocytosis of test particles by human blood monocytes (Mo) was tested in the presence of ethanol (80 mM). Phagocytosis via the Fc (IgG)‐ or C3b receptors (R) was assessed by an assay in which IgG‐ or C3b coated sheep erythrocytes (E) were used as test particles. Latex particles were tested in parallel with opsonized E. Phagocytosis of IgG‐E was reduced to 67 ± 5% of control (= without ethanol), while the corresponding value for C3b‐E was 164 ± 26% of controls. Phagocytosis of latex particles was not affected by ethanol exposure (91 ± 8% of control). The receptor functions were also tested without ethanol present during the assays. In this part of the study, Mo were incubated with or without ethanol in autologous serum for 15 min at 37 °C. After washing the cells free of ethanol, binding properties of the Fc‐R or C3b‐R were assessed by a rosette assay. Preincubation with ethanol reduced Fc‐R binding, while attachment to C3b‐R seemed to be more effective. The experiments thus indicate different effects of ethanol treatment in vitro on phagocytic receptors in human Mo. Control experiments revealed no direct effect of ethanol on the test particles.

Activation of mononuclear phagocyte functions by structurally different bacterial endotoxins.

Mononuclear phagocytes(monocytes, macrophages) are multi-potent cells with immunomodulatory properties, as well as important effector activities in inflammatory reactions (1). Much interest is at present focused on endotoxins (lipopolysaccha-ride,LPS) as modulators of the Immune response, and particularly on the relations between structure and biological activity of LPS (2). The macrophage is suggested as the central effector cell in endotoxic reactions (3), and stimulatory as well as suppressive effects on mononuclear phagocytes have been reported (4,5).