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Increased responsiveness to macrophage-activating factor (MAF) after alteration of macrophage membranes
Abstract:
Guinea pig macrophages pretreated with the esterase inhibitor, antithrombin III (AT III) show increased responsiveness to macrophage-activating factor (MAF) as demonstrated by their enhanced cytotoxicity for tumor cells. Other proteins that are not esterase inhibitors did not enhance the effect of MAF on the macrophage. Enhancement of MAF activity was also obtained when macrophages were preincubated with the cell surface reactant, diazotized sulfanilic acid (DSA). These studies indicate that the effect of MAF can be enhanced by chemical modifications of the macrophage membrane. They also provide further evidence to support the hypothesis that an esterase on the macrophage membrane modulates this cell's responsiveness to lymphocyte mediators.
Insights
Guinea pig macrophages pretreated with antithrombin III (AT III), an esterase inhibitor, showed enhanced tumor cell killing when exposed to macrophage-activating factor (MAF). Chemical modification of macrophage membranes can boost MAF activity.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophage responsiveness to lymphocyte mediators is crucial for immune responses.
- Macrophage-activating factor (MAF) is a key mediator in activating macrophages.
- The precise mechanisms modulating MAF activity on macrophages are not fully understood.
Purpose of the Study:
- To investigate whether chemical modification of the macrophage membrane can enhance responsiveness to MAF.
- To determine if esterase inhibition influences MAF-mediated macrophage activation.
- To explore the role of membrane-bound esterases in modulating macrophage activity.
Main Methods:
- Guinea pig macrophages were pretreated with antithrombin III (AT III), an esterase inhibitor.
- Macrophages were also incubated with diazotized sulfanilic acid (DSA), a cell surface reactant.
- Enhanced cytotoxicity of MAF-treated macrophages against tumor cells was measured.
Main Results:
- Pretreatment with AT III significantly enhanced MAF-induced macrophage cytotoxicity against tumor cells.
- Proteins lacking esterase inhibitory properties did not enhance MAF activity.
- Incubation with DSA also led to enhanced MAF activity, indicating chemical modification boosts MAF effects.
Conclusions:
- Chemical modifications of the macrophage membrane can enhance MAF activity.
- An esterase present on the macrophage membrane appears to modulate the cell's response to lymphocyte mediators like MAF.
- These findings support the hypothesis of a membrane-bound esterase acting as a key regulator in macrophage activation.