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Isoprenaline inhibits thromboxane B2 release from U937 cells
C E Brightling1, A J Baker, R W Fuller
1Department of Clinical Pharmacology, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
Journal of Leukocyte Biology
|May 1, 1993
Summary
U937 cells, a model for macrophages, release thromboxane B2 (TXB2). Beta 2-adrenoceptor stimulation inhibits this release in U937 cells, but not in actual macrophages, indicating a key functional difference.
Area of Science:
- Immunology
- Cell Biology
- Pharmacology
Background:
- The U937 monocytic cell line and its differentiated macrophage-like form serve as valuable in vitro models for studying human macrophages.
- These cell models exhibit characteristics similar to in vivo cells, making them useful for investigating cellular responses and mediator release.
Purpose of the Study:
- To examine thromboxane B2 (TXB2) release from undifferentiated and differentiated U937 cells upon stimulation.
- To investigate the potential modulation of TXB2 release by isoprenaline, a beta 2-adrenoceptor agonist.
- To compare the effects of beta 2-adrenoceptor stimulation on mediator release in U937 cells versus primary macrophages.
Main Methods:
- U937 monocytic cell line (undifferentiated and differentiated) stimulation with opsonized zymosan.
- Quantification of thromboxane B2 (TXB2) release using appropriate assays.
- Assessment of the inhibitory effects of flurbiprofen and isoprenaline on TXB2 release.
- Investigation of the reversal of inhibition by propranolol, a beta-adrenoceptor antagonist.
Main Results:
- Both undifferentiated and differentiated U937 cells released TXB2 in a dose-dependent manner after stimulation, with higher release from differentiated cells.
- TXB2 release was significantly inhibited by flurbiprofen and isoprenaline (a beta 2-adrenoceptor agonist).
- The inhibitory effect of isoprenaline was reversed by propranolol, confirming the involvement of beta-adrenoceptors.
Conclusions:
- Undifferentiated and differentiated U937 cells release TXB2, a process that can be inhibited by beta 2-adrenoceptor stimulation.
- This finding highlights a significant functional difference between U937 cell models and in vivo macrophages, as beta 2-adrenoceptor stimulation does not inhibit mediator release from primary macrophages.