Effects of theophylline on CD4+ T lymphocyte, interleukin-5, and interferon gamma in induced sputum of asthmatic subjects.
AIM
To investigate the mechanism of anti-inflammatory action of theophylline on asthma.


METHODS
Nineteen asthmatic subjects were administered 200 mg sustained-release theophylline twice daily for 4 weeks. The number of CD4+ T lymphocytes, eosinophils, and the levels of interleukin (IL)-5 and interferon gamma (IFN-gamma) in sputum pre- and post-administration were measured by direct immunofluorescene technique, Wright's stain and enzyme-linked immunosorbent assay, respectively. The symptom scores and lung function were also evaluated.


RESULTS
Theophylline treatment significantly improved symptom scores and FEV1.0, FEV1.0 % (P < 0.05) and reduced sputum eosinophils (P < 0.01) in asthmatic subjects. These were accompanied by a decrease in sputum IL-5 level (P < 0.01), but sputum CD4+ T lymphocytes and IFN-gamma had no significant change (P >0.05). The mean (range) serum theophylline concentration in final steady state was 7.9 (3.9 - 12.9) mg/L.


CONCLUSION
The anti-inflammatory action of theophylline in asthma may result from reduction of IL-5 production in the airways.