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Platelet-activating factor (PAF) receptor antagonists inhibit mitogen-induced human peripheral blood T-cell
P Patrignani1, S Valitutti, F Aiello
1Department of Pharmacology, Catholic University School of Medicine, Rome, Italy.
Abstract:
The addition of L-652,731 and L-653,150, two synthetic PAF-specific receptor antagonists, to 72 hour cultures of phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear leukocytes (PBML) caused a dose-dependent inhibition of (3H)-thymidine incorporation into T-cells (IC50: 25 microM and 3.2 microM, respectively). This inhibition was not reversed by exogenous interleukin (IL)-1 and IL-2. PAF receptor antagonists did not affect the expression of IL-2 receptors (TAC-antigen) on T-cells. Exogenous PAF which by itself had no significant effect on PHA-stimulated PBML proliferation, only partially reversed the inhibition of proliferation caused by PAF receptor antagonists. These results may suggest the involvement of endogenously produced PAF in the regulation of immune reactions.
Insights
Synthetic PAF receptor antagonists inhibited T-cell proliferation in human peripheral blood mononuclear leukocytes (PBML). This suggests endogenous platelet-activating factor (PAF) plays a role in regulating immune responses.
Area of Science:
- Immunology
- Cell Biology
- Pharmacology
Background:
- Platelet-activating factor (PAF) is a potent lipid mediator involved in various biological processes.
- The role of endogenous PAF in regulating human T-cell proliferation remains incompletely understood.
Purpose of the Study:
- To investigate the effect of PAF receptor antagonists on phytohemagglutinin (PHA)-stimulated human T-cell proliferation.
- To explore the involvement of endogenously produced PAF in immune regulation.
Main Methods:
- Human peripheral blood mononuclear leukocytes (PBML) were cultured with PHA.
- Cells were treated with synthetic PAF receptor antagonists (L-652,731 and L-653,150) in a dose-dependent manner.
- Incorporation of (3H)-thymidine was measured to assess T-cell proliferation.
- Effects of exogenous Interleukin-1 (IL-1), Interleukin-2 (IL-2), and PAF were evaluated.
Main Results:
- PAF receptor antagonists L-652,731 and L-653,150 significantly inhibited PHA-stimulated PBML proliferation in a dose-dependent manner (IC50: 25 microM and 3.2 microM, respectively).
- This inhibition was not reversed by exogenous IL-1 or IL-2 and did not affect IL-2 receptor expression.
- Exogenous PAF partially reversed the inhibitory effect of the antagonists, suggesting a role for endogenous PAF.
Conclusions:
- Endogenously produced PAF appears to be involved in the regulation of human T-cell proliferation.
- PAF receptor antagonists represent a potential therapeutic strategy for modulating immune responses.