In vitro effects of lipopolysaccharides and mycobacterial cell wall components on swine alveolar macrophages
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Abstract:
The possible activation of swine alveolar macrophages (AM) by lipopolysaccharides (LPS) and mycobacterial cell wall components such as muramyl dipeptide (MDP) and interphase material (IPM) was investigated. Swine AM were harvested by post mortem lung washings and the following functions were assayed: adherence and spreading in cultures; phagocytosis of 51Cr-labelled chicken red cells; cytostatic activity against xenogeneic tumour cells (P815 mastocytoma cells); monokine synthesis; interferon and LAF (lymphocyte activating factor or interleukin-1). Incubation of swine AM with either MDP, LPS or IPM (0.1 micrograms to 100 micrograms/ml) for 24 hours did not affect the cell viability but increased their adherence and spreading slightly. Phagocytosis was not markedly modified. Under the same experimental conditions, the unstimulated AM cultures exhibited a strong cytostatic activity which was not modified by these components. No interferon synthesis could be observed in the normal or stimulated AM cultures. In contrast, LAF activity was consistently increased after 48 hours of incubation with LPS, whereas MDP produced this effect only in some experiments.
Insights
Swine alveolar macrophages (AM) showed slight increases in adherence and spreading when exposed to lipopolysaccharides (LPS) and mycobacterial components. Lymphocyte activating factor (LAF) production increased with LPS stimulation.
Area of Science:
- Immunology
- Cell Biology
- Veterinary Science
Background:
- Swine alveolar macrophages (AM) are crucial immune cells in the respiratory tract.
- Understanding their activation by microbial components is key to host defense.
- Lipopolysaccharides (LPS) and mycobacterial components (MDP, IPM) are potent immune stimulators.
Purpose of the Study:
- To investigate the activation potential of LPS, muramyl dipeptide (MDP), and interphase material (IPM) on swine AM.
- To assess the effects of these components on various macrophage functions.
Main Methods:
- Swine AM were isolated via lung washings.
- Assays included adherence, spreading, phagocytosis, cytostatic activity, and cytokine/factor synthesis (interferon, LAF).
- Cells were incubated with LPS, MDP, or IPM at varying concentrations.
Main Results:
- LPS, MDP, and IPM slightly increased AM adherence and spreading without affecting cell viability.
- Phagocytic activity and cytostatic effects on tumor cells remained largely unchanged.
- No interferon synthesis was detected; however, Lymphocyte Activating Factor (LAF) production was consistently enhanced by LPS and inconsistently by MDP.
Conclusions:
- Swine AM exhibit limited activation by LPS, MDP, and IPM in terms of adherence and spreading.
- LAF production is a key response pathway for swine AM stimulated by LPS.
- Further research is needed to elucidate the full immunomodulatory role of these components in swine.