Related Experiment Videos
Effect of theophylline and adenosine on eosinophil function.
The American Review of Respiratory Disease
|August 1, 1989
Summary
Theophylline at therapeutic doses may boost eosinophil activation by blocking adenosine A2-receptors, potentially explaining its limited effect on asthma symptoms. This contrasts with high doses that inhibit eosinophil superoxide anion release.
Area of Science:
- Immunology
- Pharmacology
Background:
- Eosinophils are implicated in asthma and bronchial hyperresponsiveness.
- Theophylline's impact on eosinophil function remains unclear.
Purpose of the Study:
- To investigate the effects of theophylline on superoxide anion release from eosinophils.
- To explore the role of adenosine receptors in theophylline's action on eosinophils.
Main Methods:
- Eosinophils from guinea pigs and humans were isolated.
- Superoxide anion release was measured after stimulation with opsonized zymosan.
- The effects of theophylline, 8-phenyltheophylline, adenosine, and adenosine deaminase were assessed.
Main Results:
- Theophylline at high concentrations (10(-3) M) inhibited superoxide anion release.
- Clinically relevant concentrations of theophylline (10(-6) to 10(-5) M) potentiated release.
- 8-phenyltheophylline also potentiated release, suggesting adenosine receptor involvement.
- Adenosine reversed the potentiation, and A2-receptor selective analogs showed greater effects.
Conclusions:
- Therapeutic theophylline concentrations may enhance eosinophil activation in vivo.
- This potentiation might occur via competition with adenosine for A2-receptors.
- The findings could explain theophylline's limited efficacy in managing bronchial hyperresponsiveness related to eosinophilic inflammation.