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Guinea pig bone marrow cells treated with platelet-activating factor generate factor(s) which affects their DNA
Abstract:
We have previously reported that platelet-activating factor (PAF) induces proliferation and microbicidal activity of guinea pig bone marrow cells. In the present study, we have found that the conditioned medium of PAF- or nonmetabolizable PAF agonist-treated guinea pig bone marrow cells augmented DNA synthesis and induced microbicial activity of bone marrow cells. A PAF specific antagonist, CV-6209, inhibited generation of the active conditioned medium by PAF. Addition of the PAF antagonist only partially suppressed the augmentative effect of the active conditioned medium on DNA synthesis; this is consistent with the fact that, because of the rapid breakdown, no appreciable amount of PAF remained in the conditioned medium of PAF-treated cells. Although mouse bone marrow cells did not respond to PAF unlike guinea pig cells, their DNA synthesis was significantly enhanced by the conditioned medium of PAF-treated guinea pig bone marrow cells. Thus, some newly generated factor(s) distinct from the originally inoculated PAF seemed to modulate the bioactions of PAF on bone marrow cells. An appreciable amount of PAF was produced by calcium ionophore-treated guinea pig bone marrow cells. These findings indicate that PAF synthesized in guinea pig bone marrow cells induces generation in the cells of some factor(s) which affects proliferation or microbicidal activity.
Insights
Platelet-activating factor (PAF) stimulates guinea pig bone marrow cells. A newly generated factor in the conditioned medium enhances DNA synthesis and microbicidal activity in both guinea pig and mouse bone marrow cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- Platelet-activating factor (PAF) is known to induce proliferation and microbicidal activity in guinea pig bone marrow cells.
- The precise mechanisms by which PAF exerts these effects, particularly the involvement of secondary mediators, require further investigation.
Purpose of the Study:
- To investigate the role of conditioned medium from PAF-treated bone marrow cells on cell proliferation and activity.
- To identify potential novel factors generated by bone marrow cells in response to PAF stimulation.
Main Methods:
- Treatment of guinea pig bone marrow cells with PAF or a non-metabolizable PAF agonist.
- Collection and application of conditioned medium to assess effects on DNA synthesis and microbicidal activity.
- Utilizing a PAF-specific antagonist (CV-6209) to probe the involvement of PAF.
Main Results:
- Conditioned medium from PAF-treated cells augmented DNA synthesis and induced microbicidal activity in bone marrow cells.
- A PAF antagonist partially inhibited the augmentative effect, suggesting the involvement of PAF-independent factors.
- Mouse bone marrow cells, unresponsive to direct PAF, showed enhanced DNA synthesis upon exposure to conditioned medium from PAF-treated guinea pig cells.
- Calcium ionophore treatment induced PAF production in guinea pig bone marrow cells.
Conclusions:
- PAF synthesized within guinea pig bone marrow cells triggers the release of novel factors.
- These newly generated factors modulate bone marrow cell proliferation and microbicidal activity, impacting both autologous and heterologous cells.
- The findings reveal a complex signaling pathway involving PAF and secondary mediators in bone marrow cell regulation.