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The acquisition of anti-influenza virus activity by macrophages
Abstract:
Exposure of resident peritoneal macrophages or thioglycollate-induced macrophages (TG-Mø) to influenza or Sendai virus-infected spleen cell culture supernatants (MAS) resulted in macrophage activation. When normal resident macrophages were used as effector cells, both infected P815 and L929 cells were lysed in the presence of MAS. MAS-activated TG-Mø also lysed influenza virus-infected L929 cells. Histocompatibility between effector cells and target cells was not required for target cell destruction. The effector cells were plastic-adherent, phagocytic and Ia-. MAS-activated macrophages were also resistant to influenza virus infection in vitro. Both infectious and non-infectious preparations of influenza or Sendai virus preparations were effective at generating MAS. The mediator(s) which renders macrophages to become cytotoxic and resistant to infection was acid-stable, heat-labile (56 degrees C, 30 min; or 100 degrees C, 5 min), and the activity was neutralized by sheep antimouse type 1 interferon (IFN).
Insights
Macrophage-activating supernatants (MAS) from virus-infected cells induce macrophage cytotoxicity and viral resistance. This effect, mediated by type 1 interferon (IFN), enhances immune defense against viral infections.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Macrophages are crucial immune cells involved in host defense against pathogens.
- Viral infections can modulate macrophage function, impacting their ability to clear infected cells and resist further infection.
Purpose of the Study:
- To investigate the activation of macrophages by virus-infected cell supernatants.
- To characterize the cytotoxic and antiviral properties of activated macrophages.
- To identify the nature of the mediator responsible for macrophage activation.
Main Methods:
- Exposure of macrophages (resident peritoneal and thioglycollate-induced) to virus-infected spleen cell culture supernatants (MAS).
- Assessing macrophage-mediated lysis of infected target cells (P815, L929).
- Characterizing the properties (acid stability, heat lability) and neutralization of the MAS mediator.
Main Results:
- MAS induced macrophage activation, leading to cytotoxicity against virus-infected target cells.
- Activated macrophages exhibited resistance to influenza virus infection in vitro.
- The activating mediator was acid-stable, heat-labile, and neutralized by anti-mouse type 1 interferon (IFN).
- Histocompatibility was not required for target cell destruction.
Conclusions:
- Virus-induced macrophage activation confers cytotoxic and antiviral properties.
- Type 1 interferon is a key mediator in this process.
- Activated macrophages represent a potent defense mechanism against viral infections.