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Different effects of ethanol on particle phagocytosis via different receptors in human monocytes
1National Institute of Forensic Toxicology, Norwegian Research Council for Science and the Humanities, Oslo.
Abstract:
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% 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 degrees 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.
Insights
Ethanol exposure differentially affects human monocyte phagocytic receptors. While IgG-mediated endocytosis decreased, C3b receptor function was enhanced, impacting immune cell function.
Area of Science:
- Immunology
- Cell Biology
- Toxicology
Background:
- Human blood monocytes (Mo) play a crucial role in the immune system.
- Endocytosis is a key cellular process for monocytes, involving phagocytic receptors.
- Ethanol's impact on these specific cellular functions requires investigation.
Purpose of the Study:
- To investigate the in vitro effects of ethanol on human monocyte phagocytosis.
- To assess ethanol's influence on Fc (IgG) and C3b receptor-mediated endocytosis.
- To differentiate the effects of ethanol on receptor binding versus phagocytic activity.
Main Methods:
- Assessed phagocytosis of IgG-coated and C3b-coated sheep erythrocytes (E) and latex particles in the presence of ethanol (80 mM).
- Evaluated Fc and C3b receptor binding after preincubation of monocytes with ethanol using a rosette assay.
- Conducted control experiments to rule out direct ethanol effects on test particles.
Main Results:
- Ethanol significantly reduced IgG-mediated phagocytosis (67% of control).
- Ethanol significantly enhanced C3b-mediated phagocytosis (164% of control).
- Ethanol preincubation reduced Fc receptor binding but enhanced C3b receptor attachment.
Conclusions:
- Ethanol exhibits differential effects on human monocyte phagocytic receptors in vitro.
- Ethanol exposure impairs IgG-mediated phagocytosis while augmenting C3b receptor function.
- These findings highlight specific mechanisms by which ethanol can modulate innate immune responses.