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A novel bioaction of PAF: induction of microbicidal activity in guinea pig bone marrow cells
Abstract:
When guinea pig bone marrow cells were incubated in the presence of 10(-8) to 10(-6) M platelet activating factor (PAF) for 24 to 72 hr, microbicidal activity against Candida parapsilosis of cells was augmented. This augmentation was inhibited by PAF-specific antagonists, CV6209 or FR900452. PAF-specific binding sites with a high affinity were found on guinea pig bone marrow cells. Carrageenan or 2-chloroadenosine, reagents known to be preferentially cytotoxic to macrophages, abolished the microbicidal activity of PAF-treated bone marrow cells. Macrophages prepared from the peritoneal cavity, however, acquired no appreciable microbicidal action by treatment with PAF. These observations suggest that PAF may affect a class of guinea pig bone marrow cells through binding to receptors specific to PAF, resulting in activation and/or induction of differentiation of monocyte-macrophage lineage cells.
Insights
Platelet activating factor (PAF) enhances the ability of guinea pig bone marrow cells to kill Candida parapsilosis. This effect is mediated by PAF-specific receptors and suggests PAF activates monocyte-macrophage lineage cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- Platelet activating factor (PAF) is a potent lipid mediator involved in various biological processes.
- The role of PAF in modulating the activity of bone marrow cells, particularly their microbicidal functions, requires further elucidation.
Purpose of the Study:
- To investigate the effect of PAF on the microbicidal activity of guinea pig bone marrow cells against Candida parapsilosis.
- To identify the cellular mechanisms and specific receptors involved in PAF-mediated immune responses in bone marrow cells.
Main Methods:
- Incubation of guinea pig bone marrow cells with varying concentrations of PAF (10(-8) to 10(-6) M) for 24 to 72 hours.
- Assessment of microbicidal activity against Candida parapsilosis.
- Inhibition studies using PAF-specific antagonists (CV6209, FR900452).
- Identification of PAF-specific binding sites and assessment of cytotoxic reagent effects.
Main Results:
- PAF significantly augmented the microbicidal activity of bone marrow cells against Candida parapsilosis.
- This augmentation was reversed by PAF-specific antagonists, indicating receptor-mediated action.
- High-affinity PAF-specific binding sites were identified on bone marrow cells.
- Cytotoxic reagents targeting macrophages abolished the PAF-induced microbicidal activity, suggesting involvement of the monocyte-macrophage lineage.
Conclusions:
- PAF enhances the microbicidal capacity of a specific population within guinea pig bone marrow cells.
- These findings suggest that PAF acts through specific receptors to activate or induce differentiation of monocyte-macrophage lineage cells, thereby boosting innate immunity.