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Loss of PAF-like activity from human embryo conditioned media (ECM) following HPLC separation
L M Adamson1, V Hanf, S G Mittmann
1University Women's Hospital, University of Tübingen, FRG.
Abstract:
Recently a platelet activating factor (PAF)-like activity has been found in embryo conditioned media (ECM) and consequentially been termed embryo-derived PAF (EPAF). Yet it remains unclear whether the embryo-released molecule is in fact PAF or a PAF precursor or inductor in vivo. In this study we shall show that ECM did not induce platelet aggregation in vitro; however, it was possible to detect PAF-activity using the sensitive splenectomized mouse bioassay (SMB). Following lipid extraction, PAF activity was diminished, and after additional HPLC separation completely lost. We propose that the active fraction of ECM is lipid in nature but that this molecule is not PAF. We would rather suggest that this molecule induces the production of PAF by other cell types in vivo.
Insights
Embryo-conditioned media (ECM) contains a platelet activating factor (PAF)-like substance. This study found ECM does not directly induce platelet aggregation but likely stimulates PAF production by other cells in vivo.
Area of Science:
- Reproductive biology
- Immunology
- Biochemistry
Background:
- Embryo-conditioned media (ECM) exhibits platelet activating factor (PAF)-like activity.
- This activity has been termed embryo-derived PAF (EPAF).
- The precise nature of EPAF and its role in vivo remain unclear.
Purpose of the Study:
- To investigate whether the PAF-like activity in ECM is due to PAF itself, a precursor, or an inducer.
- To characterize the molecular nature of the active component in ECM.
Main Methods:
- In vitro platelet aggregation assays.
- Splenectomized mouse bioassay (SMB) for PAF detection.
- Lipid extraction and High-Performance Liquid Chromatography (HPLC) for molecular fractionation.
Main Results:
- ECM did not induce platelet aggregation in vitro.
- PAF-like activity was detected in ECM using the SMB.
- Lipid extraction reduced PAF activity, and HPLC abolished it.
- The active fraction from ECM is lipid-based but not PAF.
Conclusions:
- The molecule in ECM with PAF-like activity is not PAF itself.
- This molecule likely acts as an inducer, stimulating PAF production by other cell types in vivo.